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

[EX Q]: Ospreys reach sexual maturity between _ and five years of age.
[EX A]: three

[EX Q]: Covalent bonds arise when _ atoms share electrons .
[EX A]: two

[EX Q]: Atoms are extremely small, on the order of a few _ billionths of a meter.
[EX A]:
ten