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

[EX Q]: Rainforests cover less than _ percent of the Earth's surface.
[EX A]: two

[EX Q]: Older caterpillars have _ different color forms.
[EX A]: two

[EX Q]: Plants can grow and lose leaves _ or five times in a year depending on rainfall.
[EX A]:
four