What characterizes a monomial?

A monomial is characterized by being a polynomial with a single term, which aligns perfectly with the definition provided. It can also be defined as a product of a number (known as the coefficient) and one or more variables raised to non-negative integer exponents. This includes the requirement that the exponents are whole numbers, thus emphasizing that both the definitions in options A and C accurately describe characteristics of a monomial.

Since A states that a monomial is a polynomial with just one term, and C elaborates that it involves a number and variables with whole-number exponents, both definitions are indeed correct and complement each other. Therefore, the combination of these two definitions confirms that the correct answer encompasses both A and C.