Is W a subspace of the vector space? If not, state why. (Select all that apply.) W is the set of all vectors in R³ whose third component is -4. W is a subspace of R³. W is not a subspace of R³ a) Yes, W is a subspace of R³ b) No, W is not a subspace of R³ because it does not contain the zero vector. c) No, W is not a subspace of R³ because it is not closed under vector addition. d) Yes, W is a subspace of R³ because it contains the zero vector and is closed under scalar multiplication.