Which of the following subsets of R(x) are subrings of R(x) ? Justify your answer:

(a) All polynomials with a constant term.
A) Yes, it is a subring because it contains the additive identity (0) and is closed under subtraction.
B) Yes, it is a subring because it is closed under addition and multiplication.
C) No, it is not a subring because it does not contain the additive identity.
D) No, it is not a subring because it is not closed under subtraction.
E) No, it is not a subring because it is not closed under multiplication