Consider the following statements :

A. Two matrices are equal if they are of same order and their corresponding elements are equal.

B. A square matrix A is called a diagonal matrix if all its diagonal elements are zero.

C. For any matrix A, there exists a null matrix O of same order such that $A+O=O+A=A.$

D. If A is any matrix of order $m×n$ then $I_mA-A=AI_n.$ Where $I_r$ is $r×r$ identity matrix.

E. For any square matrix A. $A^3$ is obtained by taking cube of every element of A.

A, C and D only