In 1873, Spanish scientist Santiago Ramón y Cajal observed that brain fibers have distinct boundaries with clear end points,a finding that went against earlier assumptions about the brain. ____scientists had assumed that the brain was acontinuous web of fused fibers, not a vast network of distinct, individual cells.

Which choice completes the text with the most logical transition?

A)However,

B) Previously,

C) As a result,

D) Likewise,

Chimamanda Ngozi Adichie’s 2013 novel Americanah chronicles the divergent experiences of Ifemelu and Obinze, a young Nigerian couple, after high school. Ifemelu moves to the United States to attend a prestigious university. ____Obinze travels to London, hoping to start a career there. However, frustrated with the lack of opportunities, he soon returns to Nigeria.

Which choice completes the text with the most logical transition?

A) In fact,

B) Nevertheless,

C) Secondly,

D) Meanwhile,

In his 1925 book The Morphology of Landscape, US geographer Carl Sauer challenged prevailing views about how natural landscapes influence human cultures. ____Sauer argued that instead of being shaped entirely by their natural surroundings, cultures play an active role in their own development by virtue of their interactions with the environment."

Which choice completes the text with the most logical transition?

A) Specifically,

B) Finally,

C) Therefore,

D) Similarly,

“Wishcycling”—putting nonrecyclable items into recycling bins under the mistaken belief that those items can be recycled— ultimately does more harm than good. Nonrecyclable items, such as greasy pizza boxes, can contaminate recyclable materials, rendering entire batches unusable. ____nonrecyclable products can damage recycling plants’ machinery. 

Which choice completes the text with the most logical transition?

A) Fittingly, 

B) On the contrary,

C) Moreover,

D) Nevertheless,

Small, flat structures called spatulae are found at the tips of the hairs on a spider’s leg. These spatulae temporarily bond with the atoms of whatever they touch. ____spiders are able to cling to and climb almost any surface.

Which choice completes the text with the most logical transition?

A) For instance,

B) As a result

C) Similarly,

D) However,

Most of the planets that have been discovered outside our solar system orbit G-type stars, like our Sun. In 2014,____researchers identified a planet orbiting KELT-9, a B-type star more than twice as massive and nearly twice as hot as the Sun. Called KELT-9b, it is one of the hottest planets ever discovered. Which choice completes the text with the most logical transition?"

Which choice completes the text with the most logical transition?

A) likewise,

B) therefore,

C) however,

D) for example,

Etched into Peru’s Nazca Desert are line drawings so large that they can only be fully seen from high above. Archaeologists have known of the lines since the 1920s, when a researcher spotted some from a nearby foothill, and they have been studying the markings ever since. ____archaeologists’ efforts are aided by drones that capture high-resolution aerial photographs of the lines.

Which choice completes the text with the most logical transition?

A) However,

B) Still,

C) In comparison,

D) Currently,

Organisms have evolved a number of surprising adaptations to ensure their survival in adverse conditions. Tadpole shrimp (Triops longicaudatus) embryos,____can pause development for over ten years during extended periods of drought.

Which choice completes the text with the most logical transition?

A) in contrast,

B) meanwhile,

C) for example,

D) consequently,

Most conifers (trees belonging to the phylum Coniferophyta) are evergreen. That is, they keep their green leaves or needles year-round. However, not all conifer species are evergreen. Larch trees, ____lose their needles every fall.

Which choice completes the text with the most logical transition?

A) meanwhile,

B) nevertheless,

C) for instance,

D) in addition,

In 2019, researcher Patricia Jurado Gonzalez and food historian Nawal Nasrallah prepared a stew from a 4,000-year-old recipe found on a Mesopotamian clay tablet. When they tasted the dish, known as pašrūtum (“unwinding”), they found that it had a mild taste and inspired a sense of calm. ____the researchers, knowing that dishes were sometimes named after their intended effects, theorized that the dish’s name, “unwinding,” referred to its function: to help ancient diners relax.

Which choice completes the text with the most logical transition?

A) Therefore,

B) Alternately,

C) Nevertheless,

D) Likewise,