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]: Atoms are extremely small, on the order of a few ____ billionths of a meter.\Question: Choose the right answer from options given a) ten b) seven c) nine d) eight
[EX A]: a

[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]: Predation influences organisms at ____ ecological levels.\Question: Choose the right answer from options given a) four b) two c) one d) three
[EX A]:
b