Given the Assertion and Reason below, Choose one of the following responses $\begin{array}{1 1}\text{Assertion:Prothrombin is essential for blood clotting.}\\\text{Reason:Prothrombin is synthesized in the liver in the presence of }Ca^{++}.\end{array}$

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

Assertion is true but the reason is false
Hence (C) is the correct answer.