Assertion (A) : If $\left[\begin{array}{cc}\mathrm{x}& 1\\ 1& 0\end{array}\right]$ is an idempotent matrix then x = 0 

Reason(R) : If A is an idempotent matrix then ${\mathrm{A}}^2 = \mathrm{A}$

Both A and R are true but R is not  correct explanation of A 

Both A and R are true and R is the correct explanation of A 

A is false R is true

 A is true R is false