Since the direction of the force and the direction of the path is perpendicular, the person is not doing any physical work.
See projectiles are very simple unless you understand its core concepts....projectile is nothing just mixture of upward motion and horizontal motion....
THE KEY IS FORGET THE NAME PROJECTILE...ITS JUST HORIZONTAL MOTION + VERTICAL MOTION
15 degrees because a glass of water won't do anything to a bath tub of 15 degree water
C. Is the da answer to your question!