c
\(\begin{array}{l}
Net\,{\rm{ distance}}\,travellel\,along\,y - direction\\
{s_y} = 6\,\cos \,{45^ \circ }\hat j - 4\,\cos \,{45^ \circ }\hat j\\
 = 10 \times \frac{1}{{\sqrt 2 }} = 5\sqrt 2 \,km\\
\therefore \,Net\,{\rm{distance}}\,travelled\,from\,the\,starting\\
{\rm{point}},
\end{array}\)

\(\begin{array}{l}
S = \sqrt {{s_x}^2 + {s_y}^2}  = \sqrt {{{\left( {\sqrt 2 } \right)}^2} + {{\left( {5\sqrt 2 } \right)}^2}} \\
 = \sqrt {2 + 25 \times 2}  = \sqrt {52} \,km\\
Angle\,which\,the\,r{\rm{esultanl}}\,{\rm{makes}}\,{\rm{with}}\,{\rm{the}}\\
{\rm{east}}\,{\rm{direction}}\\
\tan \theta  = \frac{y}{x} = \frac{{5\sqrt 2 }}{{\sqrt 2 }}\,\,\,\,\,\,\,\,\,or\,\theta \, = {\tan ^{ - 1}}\left( 5 \right)\,
\end{array}\)