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').
--------
Question: Nightmares happen frequently in childhood, especially between the ages of ____ and six.\Question: Choose the right answer from options given a) three b) eight c) no d) ten

Answer: a


Question: Organisms have ____ forms of nucleic acid.\Question: Choose the right answer from options given a) four b) three c) two d) one

Answer: c


Question: Light only penetrates the upper hundred, sometimes even only the upper ____ meters of the water.\Question: Choose the right answer from options given a) two b) no c) zero d) ten

Answer:
d