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:
Anthrax usually is a fatal disease with ____ symptoms observed.\Question: Choose the right answer from options given a) no b) seven c) one d) six

Ex Output:
a


Ex Input:
Younger children can produce as much as ____ times more saliva than adults.\Question: Choose the right answer from options given a) one b) ten c) five d) eight

Ex Output:
d


Ex Input:
Naiads have ____ caudal filaments and external gills.\Question: Choose the right answer from options given a) ten b) eight c) two d) five

Ex Output:

c