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').

Black widows mature in ____ to four months.\Question: Choose the right answer from options given a) two b) seven c) eight d) zero
a

Most endocrinologists see patients every ____ months throughout the pregnancy.\Question: Choose the right answer from options given a) six b) two c) zero d) three
b

Altimetric satellites are usually limited life missions lasting approximately three to ____ years.\Question: Choose the right answer from options given a) five b) ten c) four d) eight

b