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]: Pneumatic motor is a six-point unit with ____ pneumatics facing up and three facing down.\Question: Choose the right answer from options given a) five b) no c) three d) nine
[EX A]: c

[EX Q]: Stable oxygen has eight protons and ____ neutrons.\Question: Choose the right answer from options given a) eight b) ten c) three d) zero
[EX A]: a

[EX Q]: Some penguins stay in the water for up to ____ months without coming to land.\Question: Choose the right answer from options given a) zero b) nine c) three d) five
[EX A]:
d