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

[EX Q]: Men produce brand new sperm every _ to three months.
[EX A]: two

[EX Q]: Excess potassium induces larval metamorphosis in _ marine invertebrate species.
[EX A]: four

[EX Q]: Males can reproduce each year, and females reproduce on average only once every _ years.
[EX A]:
four