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

[EX Q]: Induction also operates early in development, even before the _ layered embryo forms.
[EX A]: three

[EX Q]: Some manatees have _ or four nails on the tip of each flipper.
[EX A]: three

[EX Q]: Every eagle is made from twelve different species of feathers, from _ different countries.
[EX A]:
eight