Which pairs from the following list of three-dimensional vectors are.perpendicular to one another? \begin{array}{l} \mathbf{A}=12 \boldsymbol{i}-7 \boldsymbol{j}+\boldsymbol{k} \\ \mathbf{B}=6 \boldsymbol{i}+\boldsymbol{k} \\ \mathbf{C}=3 \boldsymbol{i}+5 \boldsymbol{j}-18 \boldsymbol{k} \end{array} Note: here, i, j,

and k refer to the unit vectors i-hat, j-hat, and k-hat. 1) A and B 2) B and C 3) A and C 4) A, B, and C 5) None of the above