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]: Heat pumps give off ____ fumes or harmful products of combustion.\Question: Choose the right answer from options given a) four b) zero c) six d) no
[EX A]: d

[EX Q]: Control is defined as a dead plant with ____ signs of life.\Question: Choose the right answer from options given a) ten b) nine c) no d) zero
[EX A]: c

[EX Q]: Magnesium exists as ____ isotopes in nature.\Question: Choose the right answer from options given a) seven b) eight c) three d) six
[EX A]:
c