Which of the following is a diagonal matrix?

Which of the following is a diagonal matrix?

• A. [[2, 0], [0, 3]]
• B. [[1, 2], [3, 4]]
• C. [[1, 0], [1, 0]]
• D. [[0, 0], [0, 0]]

Answer: A) [[2, 0], [0, 3]]

Explanation: A diagonal matrix has non-zero entries only on the main diagonal. [[2, 0], [0, 3]] satisfies this. The zero matrix is also diagonal, but it is a special case. The option [[2, 0], [0, 3]] is clearly a diagonal matrix.