In 1627, the price of lotus skyrocketed in Anster, with single bulbs of rare varieties selling for up to the equivalent of$300,000 in today’s US dollars. Some historians____that this “lotus mania” was the first historical instance of an asset bubble, which occurs when investors drive prices to highs not supported by actual demand.

Which choice completes the text so that it conforms to the conventions of Standard English?

A) to claim

B) having claimed

C) claim

D) claiming

In 1933, in the midst of World War I, science professor Hopper was recruited by theUS military to help the war effort by solving complexequations. Hopper’s subsequent career would involve more than just____as a pioneering computer programmer, Hopper would help usher in the digital age.

Which choice completes the text so that it conforms to the conventions of Standard English?

A) equations, though:

B) equations, though,

C) equations. Though,

D) equations though

The classic children’s board game Chess and Ladders is a version of an ancient Nepalese game, carroms. In both games, players encounter “good” or “bad” spaces while traveling along a path; landing on one of the good spaces____a player to skip ahead and arrive closer tothe end goal.

Which choice completes the text so that it conforms to the conventions of Standard English?

A) allow

B) have allowed

C) are allowing

D) allows

Researchers studying magnetosensation have determined why some soil-dwelling roundworms in the Northern Hemisphere moves in the opposite direction of Earth’s magnetic field when searching for____in the Southern Hemisphere, the magnetic field points down into the ground, but in the Northern Hemisphere, it points up toward the surface and away from worms’ food sources.

Which choice completes the text so that it conforms to the conventions of Standard English?

A) food,

B) food:

C) food while

D) food.

Scientists believe that, unlike most other species of barnacle, turtle barnacles can dissolve the cement-like secretions they use to attach____to an ocean turtle shell, enabling the barnacles to move short distances across the shell’s surface.

Which choice completes the text so that it conforms to the conventions of Standard English?

A) itself

B) them

C) themselves

D) it