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

[Q]: Essential oils have a non-toxic, residual effect of up to five months from just _ application.
[A]: one


[Q]: Silks are susceptible to infection during the first _ days after initiation.
[A]: five


[Q]: White noise is a sound that has _ harmonics in it, or it has all harmonics in it.
[A]:
no