Which statement correctly expresses the defining property of a polynomial?

All variable exponents are positive whole numbers (1, 2, 3, ...), and constants are allowed as degree zero terms

All variable exponents in the expression are considered nonnegative integers (0, 1, 2, 3, ...)

An expression is a polynomial if it has at most three terms separated by addition or subtraction signs

An expression is a polynomial as long as the coefficients are integers and there are no fractional coefficients in front of the variables