Given, vector, $\mathbf{A}=\hat{\mathbf{i}}-\hat{\mathbf{j}}+2 \hat{\mathbf{k}}$ and vector $\mathbf{B}=3 \hat{\mathbf{i}}-3 \hat{\mathbf{j}}+6 \hat{\mathbf{k}}$, then which one of the following statements is true?
(a) $A$ is perpendicular to $B$
(b) $A$ is parallel to $B$
(c) Magnitude of $A$ is half of that of $B$
(d) Magnitude of $B$ is equal to that of $A$