Which expressions are polynomials a) 20x^2 b)20x^2/y c)20x^2+y^1/2

The answer is the option A: A) 20x^2

 The explanation is shown below:

 1. The polynomials can't have:

 - Fractional exponents.
 - Variables in the denominator.

 2. As you can see, the option B) 20x^2/y has the variable "y" in the denominator, Therefore, it is not a polynomial.

 3. The option C) 20x^2+y^1/2 has a fractional exponent, so it is not a polynomial.