In this task, find the most appropriate number to replace the blank (indicated with _ ) and express it in words.

[EX Q]: All butterflies have _ pairs of legs.
[EX A]: three

[EX Q]: Death usually occurs by five to _ years of life due to pneumonia or other infections.
[EX A]: eight

[EX Q]: Flu strikes within _ to three days after exposure to the virus.
[EX A]:
one