A man rows a boat with a speed of 18 km/hr in northwest direction. The shoeline makes an angle of `15^(@)` south of west. Obtain the component of the velocity of the boat along the shoreline:
A. 9 km/hr
B. `18 sqrt(3)/2` km/hr
C. `18 cos 15^(@)` km/hr
D. `18 cos 75^(@)` km/hr