Which one of the following sets is not a vector subspace of
(A)
None of them
(B)
\boxed{\text{(A) None of them}} is the final answer since all three conditions are satisfied.
Step 1 :Check if the zero vector is in the set:
Step 2 :Check if the set is closed under vector addition:
Step 3 :Check if the set is closed under scalar multiplication:
Step 4 :\boxed{\text{(A) None of them}} is the final answer since all three conditions are satisfied.