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

[EX Q]: Tetrachoric correlation is _ artificially dichotomous variables.
[EX A]: two

[EX Q]: Most insects have _ wings, but dipterans have only two.
[EX A]: four

[EX Q]: Penguins live on _ different continents.
[EX A]:
four