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:
Chlorine is manufactured in ____ ways.\Question: Choose the right answer from options given a) four b) two c) nine d) seven

Ex Output:
b


Ex Input:
Ultrasonic liposuction fits into ____ categories.\Question: Choose the right answer from options given a) two b) seven c) nine d) one

Ex Output:
a


Ex Input:
Insomnia can be short-lived, lasting only one to ____ nights.\Question: Choose the right answer from options given a) five b) eight c) no d) two

Ex Output:

d