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

[Q]: Cormorants are monogamous and breed in colonies of up to _ thousand pairs.
[A]: three


[Q]: Prostate cancer is categorized in _ stages.
[A]: four


[Q]: Ocular dryness responds to the use of artificial tears applied every _ to three hours.
[A]:
one