Concept:A subset means every element of one set is contained inside another set.Explanation:If set B is a subset of set A, then every member of B is also a member of A.This does not mean both sets must have the same number of elements.It also does not mean that only some members or no members of B are in A.The correct condition is that all the members of set B are present in set A.Answer:Option D: all the members of set B are in set A.