-1 is not the answer because when you plug -1 into the equation you will end up with an imaginary number. Remember:
-1^2 = - (1 * 1) = -1 and the sqroot of a negative number gives you an imaginary number. Some might be mislead by thinking that x^2 is (x)^2, which it is not.
The answer cannot be zero because you are told that x is not zero. If x is zero, that gives you a zero in the numerator and denominator. Anything divided by a zero is undefined.
It will not be x, because xs will cancel out.
Let me make it easier for you. Stop thinking about plugging in numbers on this one.
When you simplify sqroot x^2 you end up with + or - x. You need to get rid of the or.
Therefore, to get the answer, you take the absolute value of x over x. That is as far as you simplify the expression.