A giant gorilla who is terrorizing the city grabs a wrecking ball by the cable attached to it. The gorilla swings the ball clockwise in a large, vertical circle. The angle between the vertical and the position of the cable is θ, as shown. The cable slips from the gorilla's grasp. In order for the ball to fly straight up into the air when the gorilla loses his grip, θ should be closest to: a. 90
b. 180
c. 135
d. 45