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]: 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]: Most people have ____ kidneys.\Question: Choose the right answer from options given a) two b) five c) seven d) six
[EX A]: a

[EX Q]: Sponges have ____ nervous system and no specialised sensory cells.\Question: Choose the right answer from options given a) two b) four c) no d) eight
[EX A]:
c