Detailed Video Solution: https://www.youtube.com/watch?v=v5v-AfpwicQ&list=PLIPZ2_p3RNHige8KFyCc4uWDx2uXEq1f0&index=6
Let $R = \{1, 2\} \text{ and } S = \{2, 3\}$
A. $R \cap S=(R \cup S)-[(R-S) \cup(S-R)]$
$$
\{2\}=\{1,2,3\}-[\{1\} \cup\{3\}]
$$
$$
\{2\}=\{2\}
$$
B. $R \cup S=(R \cap S)-[(R-S) \cup(S-R)]$
$$
\{1,2,3\} \neq\{2\}-[1,3]
$$
c. $R \cap S=(R \cup S)-[(R-S) \cap(S-R)]$
$$
\{2\} \neq\{1,2,3\}-[1 \cap 3]
$$
D. $R \cap S=(R \cup S) \cup(R-S)$
$$
\begin{aligned}
& \{2\}=\{1,2,3\} \cup\{1\} \\
& \{2\} \neq\{1,2,3\}
\end{aligned}
$$
Hence. Option(A) $R \cap S=(R \cup S)-[(R-S) \cup(S-R)]$ is the correct choice.