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

Input: Consider Input: Every insect has _ legs, has six legs, has six legs.

Output: six

Input: Consider Input: Diatoms look like _ shells that fit together.

Output: two

Input: Consider Input: Saliva consists of _ fluids, 'mucous' and 'serous'.
Output: two