In this item, I assume that the number written is square root of 7. Square root of 7 is an irrational number that when multiplied to itself will give a rational value. That is,
(square root of x)(square root of x) = x
By using the same principle,
(square root of 7)(square root of 7) = 7
7 now as the answer is a rational number.
Thus, the answer is the third choice.
