$\sim r$ is true $\rightarrow r$ is false. Therefore (A) is not the answer.
Also, $q \rightarrow r$ is true and $r$ is false $\rightarrow q$ is false. Therefore (C) is not the answer.
Similarly, since $q$ is false and $p \rightarrow q$ is true, $p$ must be false $\rightarrow$ (D) is the answer, not (B)