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').

[EX Q]: Redwoods reproduce ____ ways.\Question: Choose the right answer from options given a) zero b) two c) six d) nine
[EX A]: b

[EX Q]: Honeybees have ____ jobs.\Question: Choose the right answer from options given a) ten b) one c) three d) two
[EX A]: d

[EX Q]: Retinoic acid regulates oral epithelial differentiation by ____ mechanisms.\Question: Choose the right answer from options given a) two b) five c) six d) ten
[EX A]:
a