Craig's Interpolation Theorem states that if $A \implies B$ is a classical tautology, there exists a formula $C$ containing only propositional variables common to both $A$ and $B$ such that $A \implies C$ and $C \implies B$ are both tautologies. Given the classical implication $A \implies B$ where $A = (P \lor Q) \land (\neg P \lor R)$ and $B = Q \lor R \lor S$, which of the following is a valid Craig interpolant $C$?