TASK DEFINITION: In this task, find the most appropriate number to replace the blank (indicated with _ ) and express it in words.
PROBLEM: Essential oils have a non-toxic, residual effect of up to five months from just _ application.

SOLUTION: one

PROBLEM: Infertility affects one in _ couples and affects both men and women.

SOLUTION: seven

PROBLEM: Oceanographers have _ theories on rip current formation.

SOLUTION:
two