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 Q]: Chemical interactions are essentially electron interactions of ____ atoms.\Question: Choose the right answer from options given a) six b) no c) ten d) two
[EX A]: d

[EX Q]: Today there are ____ UK hospitals doing heart transplants.\Question: Choose the right answer from options given a) three b) five c) six d) nine
[EX A]: d

[EX Q]: Malaria kills up to ____ million people a year - mostly children and pregnant women.\Question: Choose the right answer from options given a) ten b) three c) seven d) five
[EX A]:
b