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').

Heat pumps give off ____ fumes or harmful products of combustion.\Question: Choose the right answer from options given a) four b) zero c) six d) no
d

Lions have ____ distinct vocalizations including roars, grunts and growls.\Question: Choose the right answer from options given a) eight b) six c) four d) nine
d

Females are able to conceive three to ____ months after calves are weaned.\Question: Choose the right answer from options given a) four b) five c) six d) ten

a