In this task, find the most appropriate number to replace the blank (indicated with _ ) and express it in words.
--------
Question: Every insect has _ legs, has six legs, has six legs.

Answer: six


Question: Excess potassium induces larval metamorphosis in _ marine invertebrate species.

Answer: four


Question: Travellers tend to marry young, and the average family size is _ children.

Answer:
eight