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

[EX Q]: Ozone is a form of oxygen in which the molecule contains _ atoms instead of two.
[EX A]: three

[EX Q]: Postpartum blues are common during the _ months after childbirth.
[EX A]: three

[EX Q]: Pure phosphorus exists in _ forms - red, white, yellow.
[EX A]:
three