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

[EX Q]: Southern moles are six to seven inches long and weigh _ to four ounces.
[EX A]: three

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

[EX Q]: Healthy people can donate blood as often as once every _ weeks.
[EX A]:
eight