Given the Assertion and Reason below, Choose one of the following responses $\begin{array}{1 1}\text{Assertion:The stem cells of bone marrow have lymphocytes and these occur in the blood,lymph and connective tissues.}\\\text{Reason:Lymphocytes migrate to bursal lymphoid tissue or to thymus and differentiate into B or T-cells.}\end{array}$

Question

$\begin{array}{1 1}(A)\;\text{Both assertion and reason are true and the reason is a correct explanation of the assertion}\\(B)\;\text{Both assertion and reason are true but reason is not a correct explanation of the assertion}\\(C)\;\text{Assertion is true but the reason is false}\\(D)\;\text{Both assertion and reason are false}\end{array}$