A projectile of mass \(m\) is launched from horizontal ground at time \(t = 0\) with an initial velocity directed at an angle \(\theta\) above the horizontal, where \(0 < \theta < 90^\circ\). The projectile moves under the influence of a uniform downward gravitational acceleration \(g\) with negligible air resistance and returns to the ground at time \(t_f\). Which of the following graphs best represents the instantaneous power \(P\) delivered by the gravitational force to the projectile as a function of time \(t\) between \(t = 0\) and \(t = t_f\)?