Consider the Equilibrium a + B $\leftrightarrows$ CWhat Is Significant About the Equilibrium State in Which [B]

Consider the equilibrium A + B $\leftrightarrows$ C.What is significant about the equilibrium state in which [B] = [C]?

A) [A] = K
B) [A] = [B] = [C]
C) [B] = [C] = K
D) [A] = 1/K
E) [C]/[B] = K