Answer
The tension in the vine is greater in magnitude than the gravitational force on Tarzan.
Work Step by Step
At the bottom of the swing, the tangential acceleration is zero. Tarzan is moving in circular motion so the acceleration points toward the center of the circle, in this case, straight up. Therefore, the net force must be directed straight up. Therefore, the tension in the vine (which points straight up) is greater in magnitude than the gravitational force on Tarzan (which points straight down).
