Question

Let $A$ and $B$ be two non-empty subsets of set $X$ such that $A$ is not a subset of $B$, then which of the following is always true?

• A. $A$ is a subset of the complement of $B$
• B. $B$ is a subset of $A$
• C. $A$ and $B$ are disjoint
• D. $A$ and the complement of $B$ are non-disjoint.

Answer 1

Answer: (D)

$A$ and the complement of $B$ are non-disjoint.

Since A is not a subset of B, complement of B contains A. Hence A and complement of B are not disjoint.