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').

Interdigital glands are present on all ____ feet, and are slightly larger on the front feet.\Question: Choose the right answer from options given a) three b) five c) four d) eight
c

Most bioluminescence is blue for ____ reasons.\Question: Choose the right answer from options given a) seven b) two c) four d) zero
b

Precocial birds learn to forage within ____ or four days.\Question: Choose the right answer from options given a) no b) three c) eight d) six

b