If expression A = (mn + 4 − 3) and B = (−2mn + 3), A + B equals:

This question tests the ability to add algebraic expressions by combining like terms. First, simplify expression A, then add it to expression B.

• Simplify A: A = mn + 4 - 3 = mn + 1.
• Now, add A and B: A + B = (mn + 1) + (-2mn + 3).
• Combine the 'mn' terms: mn + (-2mn) = mn - 2mn = -mn.
• Combine the constant terms: 1 + 3 = 4.
• Correct Option B: −mn + 4 is accurate because combining the simplified expressions yields -mn + 4.
• Option A: −mn + 3 is incorrect as the constant term would be 3 if A was mn+2.
• Option C: mn + 6 is incorrect as the 'mn' term is wrong and the constant term is wrong.
• Option D: −mn + 1 is incorrect as the constant term would be 1 if B was -2mn.