Polynomials are closed under the operation of multiplication.

Which statement best explains the meaning of closure of polynomials under the operation of multiplication?

A. When any two polynomials are multiplied, the result is always a polynomial with positive coefficients.
B. When any two polynomials are multiplied, the result is always a polynomial.
C. When any two polynomials are multiplied, the result is always a monomial or a binomial.
D. When any two polynomials are multiplied, the coefficients of terms are always multiplied.