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').

Stable oxygen has eight protons and ____ neutrons.\Question: Choose the right answer from options given a) eight b) ten c) three d) zero
a

Nymphs emerge in ____ to seven days and flatten themselves against the leaf to feed.\Question: Choose the right answer from options given a) one b) five c) nine d) two
b

Cows can detect odours up to ____ miles away.\Question: Choose the right answer from options given a) ten b) five c) three d) no

b