Answer: Choice A) Rational
======================================================
Reasoning:
Apply the rule that

The squaring operation and square root operation cancel each other out. This is because they are inverses of one another.
For example, 7^2 = 49, and the square root of this leads back to 7.
Going back to the problem at hand, we can say,

Then we can write that '12' at the end as 12/1. This is a ratio or fraction of integers, which makes the number rational.
Any rational number is of the form a/b, where a,b are integers and b is nonzero.