A polynomial is an expression containing two or more algebraic terms. They are often the sum of several terms containing different powers (exponents) of variables and never contains square roots or division by a variable.
In your case, option A contains two terms that with second and first power of x. Therefore, the expression in A is a polynomial. Option B contains three terms that with second, first power of x and coefficient. This is a polynomial too. Option C represents the absolute value of x and doesn't represent a polynomial.
