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:
Food chains consist of ____ trophic levels.\Question: Choose the right answer from options given a) ten b) three c) one d) four

Ex Output:
d


Ex Input:
Waves can sometimes reach ____ feet tall, while still being playful and fun.\Question: Choose the right answer from options given a) nine b) eight c) ten d) no

Ex Output:
c


Ex Input:
Parrots have the intelligence of a ____ year old, but the emotions of a three year old.\Question: Choose the right answer from options given a) five b) six c) eight d) ten

Ex Output:

a