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').

Ex Input:
Mares abort suddenly without signs of illness, and the fetus shows ____ signs of degenerative change.\Question: Choose the right answer from options given a) zero b) no c) seven d) ten

Ex Output:
b


Ex Input:
Respiratory therapists complete ____ to four years of education.\Question: Choose the right answer from options given a) one b) nine c) zero d) two

Ex Output:
d


Ex Input:
Hexapods comprise insects and ____ small orders of insect-like animals with six thoracic legs.\Question: Choose the right answer from options given a) seven b) three c) two d) one

Ex Output:

b