TASK DEFINITION: Given a sentence with a missing word, pick the answer option that best fills out the missing word in the sentence. Indicate each answer with its index ('a', 'b', 'c', 'd').
PROBLEM: Some motors contain ____ gears and spin very fast, and have little if any torque.\Question: Choose the right answer from options given a) four b) three c) five d) no

SOLUTION: d

PROBLEM: Atoms are extremely small, on the order of a few ____ billionths of a meter.\Question: Choose the right answer from options given a) ten b) seven c) nine d) eight

SOLUTION: a

PROBLEM: Some herpesvirus genomes exist as a mixture of ____ isomers.\Question: Choose the right answer from options given a) one b) eight c) zero d) four

SOLUTION:
d