Which of the following statements is true?
(a) Every zero matrix is a square matrix
(b) A unit matrix is a diagonal matrix
(c) \(\begin{bmatrix}1&0\\[0.3em]0&1\end{bmatrix}\) is the identity matrix for addition of 2 × 2 matrix
(d) \(\begin{bmatrix}4&x\\[0.3em]1&3\end{bmatrix}\) = \(\begin{bmatrix}4&5\\[0.3em]1&0\end{bmatrix}\), if x = 5