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').

Example Input: Elephants have four molars, which are replaced ____ times, for a total of six sets in a lifetime.\Question: Choose the right answer from options given a) five b) no c) three d) one
Example Output: a

Example Input: Plants have at least ____ sHSP gene families which comprise a large multigene family.\Question: Choose the right answer from options given a) zero b) eight c) five d) seven
Example Output: c

Example Input: Garlic mustard has a ____ year life cycle.\Question: Choose the right answer from options given a) two b) six c) nine d) ten
Example Output:
a