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').

Chlorine has ____ naturally occurring isotopes.\Question: Choose the right answer from options given a) nine b) eight c) three d) two
d

Mountain goats have ____ sharp horns.\Question: Choose the right answer from options given a) two b) six c) ten d) four
a

Lobsters are slow growing and it takes five to ____ years for a female to reach maturity.\Question: Choose the right answer from options given a) two b) eight c) zero d) six

d