With respect to the given assertion and reason, choose the correct option.
Assertion (A): The process in which meristematic cells attain permanent shape, size and function is called differentiation.
Reason (R): Cells of meristematic tissue differentiate to form different types of permanent tissue.
Meristematic cells differentiate to form different types of permanent tissue. The process by which meristematic cells specialise to perform a particular function is called cell differentiation.