Mark against the correct answer in each of the following:

Mark $(\sqrt{)}$ against the correct answer in each of the following:

If the vectors $\overrightarrow{\mathrm{a}}=3 \hat{\mathrm{i}}+\hat{\mathrm{j}}-2 \hat{\mathrm{k}}$ and $\overrightarrow{\mathrm{b}}=\hat{\mathrm{i}}+\lambda \hat{\mathrm{j}}-3 \hat{\mathrm{k}}$ are perpendicular to each other then $\boldsymbol{\lambda}=$ ?

A. $-3$

B. $-6$

C. $-9$

D. $-1$