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

[EX Q]: Knives have _ cutting edges for double cutting life.
[EX A]: two

[EX Q]: Bacteria acquire genes for resistance in _ ways.
[EX A]: three

[EX Q]: Amphibians are the first true vertebrates with _ limbs.
[EX A]:
four