The equation of the plane containing the lines \[\mathbf{r}={{\mathbf{a}}_{1}}+\lambda {{\mathbf{a}}_{2}}\] and \[\mathbf{r}={{\mathbf{a}}_{2}}+\lambda {{\mathbf{a}}_{1}}\] is

• A. \[[\mathbf{r}\,\ {{\mathbf{a}}_{1}}\ \,{{\mathbf{a}}_{2}}]=0\]
• B. \[[\mathbf{r}\ \,{{\mathbf{a}}_{1}}\ \,{{\mathbf{a}}_{2}}]={{\mathbf{a}}_{1}}.\ {{\mathbf{a}}_{2}}\]
• C. \[[\mathbf{r}\ \,{{\mathbf{a}}_{2}}\ \,{{\mathbf{a}}_{1}}]={{\mathbf{a}}_{1}}.\ {{\mathbf{a}}_{2}}\]
• D. None of these