(A) scalar matrix
(B) diagonal matrix
(C) skew-symmetric matrix
(D) symmetric matrix
Choose the correct answer from the options given below:

If  $$n×n$$ matrix A has only one non-zero element, rank of  A is

If $$I$$ be the $$2×2$$ identity matrix and $$A = \begin{pmatrix} 2 & -1 \\-1 & 2\end{pmatrix}$$, then $$A^2$$ is equal to​