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

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


[Q]: Most smokers try to quit at least _ or six times before they succeed, researchers say.
[A]: five


[Q]: Crustaceans have _ types of feelers.
[A]:
two