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').

Q: Bulls can stand as tall as ____ feet at the shoulders.\Question: Choose the right answer from options given a) one b) five c) seven d) four

A: b
****
Q: 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

A: a
****
Q: Chemical explosives are of ____ general kinds.\Question: Choose the right answer from options given a) ten b) two c) one d) nine

A:
b
****