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]: Avian kidneys have ____ kinds of nephrons.\Question: Choose the right answer from options given a) four b) eight c) no d) two
[EX A]: d

[EX Q]: Mechanical digestion occurs as ____ strong layers of muscle contract to produce a churning motion.\Question: Choose the right answer from options given a) four b) no c) three d) six
[EX A]: c

[EX Q]: Automatic weapons have ____ specific uses in military tactics.\Question: Choose the right answer from options given a) no b) nine c) two d) ten
[EX A]:
c