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').

Harbor porpoises live in groups averaging one to ____ individuals and are very skittish.\Question: Choose the right answer from options given a) seven b) five c) two d) three
d

Ascidian tunicates come in ____ main forms.\Question: Choose the right answer from options given a) three b) zero c) four d) eight
a

Bull trout reach maturity in four to ____ years and live as long as twelve years.\Question: Choose the right answer from options given a) ten b) three c) seven d) eight

c