Identify which Boolean expression is already in a minimal two-level form and therefore cannot be simplified further using basic Boolean algebra rules. Select the equation that cannot be further reduced in literal count or gate count (at the two-level SOP/POS level).

Introduction / Context:
Boolean simplification aims to reduce literal count and gate depth while preserving functionality. Some expressions are already minimal in a two-level implementation (sum-of-products or product-of-sums). Recognizing them avoids unnecessary algebra and helps in mapping to standard cells efficiently (e.g., XOR/XNOR implementations).

Given Data / Assumptions:

• We compare several common expressions for reducibility.
• “Further simplified” means fewer literals or fewer product/sum terms at the same two-level form.
• No exploitation of multi-level factorization beyond standard two-level simplification is intended.

Concept / Approach:
Some identities: A + AB = A (absorption). A + A'B = A + B (consensus/absorption). AB + AB' = A(B + B') = A (complementation). However, AB + A'B' represents equivalence (XNOR) between A and B, which in two-level SOP uses two distinct product terms and cannot be reduced to a single literal or a single product term without introducing an XOR/XNOR gate primitive or changing the level of logic.

Step-by-Step Solution:

Verification / Alternative check:

Why Other Options Are Wrong:

Common Pitfalls:

Final Answer: