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

[EX Q]: Mares generally give birth to one young every _ years.
[EX A]: three

[EX Q]: Most smokers try to quit at least _ or six times before they succeed, researchers say.
[EX A]: five

[EX Q]: Natural gas is lighter than air, non-toxic and contains _ poisonous ingredients.
[EX A]:
no