Assertion(A): Graphite is an example of tetragonal system.

Reason ( R) : For tetragonal system a=b=c; $\alpha =\beta ={90}^{\circ } \gamma ={120}^{\circ }$

Choose the correct option from the following

A is true but R is false

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

Both A and R are false

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