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

[EX Q]: Animals develop either two or _ embryonic germs layers .
[EX A]: three

[EX Q]: Most litters have two to _ kittens.
[EX A]: four

[EX Q]: Theobroma oil can exist in _ different polymorphic forms of which only one is stable.
[EX A]:
four