You are given a fraction in simplest form. the numerator is not zero. when you write the fraction as a decimal, it is a repeating decimal. which numbers from 1 to 10 could be the denominator?
when the denominator is
[? ], [? ], [? ], or [? ] the result will be a repeating decimal.

You could easily do that yourself, with a pencil, and about the same amount of time it took you to post the question here.

If you go through and try them . . . 1/1,  1/2,  1/3,  1/4, 1/5 . . . etc., you'll find
that the thirds, sixths, sevenths, and ninths produce repeating decimals.
The oneths, tooths, fourths, fifths, eighths, and tenths don't.