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

SOLUTION: d

PROBLEM: Pupae usually transform into adults ____ to three days later.\Question: Choose the right answer from options given a) one b) two c) no d) eight

SOLUTION: b

PROBLEM: Smokers run ____ times the risk of sudden death compared with non-smokers.\Question: Choose the right answer from options given a) three b) two c) zero d) one

SOLUTION:
a