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

[Q]: Humans host _ species of louse, the head louse , the body louse and the pubic louse .
[A]: three


[Q]: Rye grasses germinate in _ days.
[A]: six


[Q]: White men are _ times more likely to develop testicular cancer than black men.
[A]:
four