Is x > y?

(1) sqrt x > y

If x = 9 and y = 2. sqrt x > y and x > y.
If x = 1/4 and y = 1/3. sqrt x > y and x < y.
Since, we don't have a definite answer. Statement I is insufficient to answer the question.

(2) x^3 > y

If x = 2 and y = 1. x^3 > y and x > y.
If x = -1/2 and y = -1/3. x^3 > y and x < y.
Since, we don't have a definite answer. Statement II is insufficient to answer the question.

From I and II combined

Since √x is mentioned in the first statement, we can tell that the value of x is greater than 0.
Since x^3>y and √x>y, the value of x should be greater than 1. For any x,y where x>1, if x^3>y then x is definitely greater than y. So Statement I+II combined is sufficient to answer the question.

Answer C

I will post a graphical solution in a bit!