If A is a 3×3 matrix with trace(A) = 0 and A is skew-symmetric, then the sum of all elements of A is:

If A is a 3×3 matrix with trace(A) = 0 and A is skew-symmetric, then the sum of all elements of A is:

• A. 0
• B. 6
• C. 3
• D. Cannot be determined

Answer: A) 0

Explanation: In a skew-symmetric matrix, diagonal elements are 0, and for i ≠ j, aⱼᵢ = −aᵢⱼ. So the sum of all elements is ∑ aᵢⱼ = sum of diagonals + sum of pairs (aᵢⱼ + aⱼᵢ) = 0 + 0 = 0.