Final answer:
Tarzan's acceleration at the lowest point of his swing is zero.
Step-by-step explanation:
In order to determine Tarzan's acceleration at the lowest point of his swing, we need to consider the forces involved. At the lowest point, Tarzan is at the extreme of his swing and hanging motionless. The only force acting on Tarzan is his weight, which is the force exerted on him by Earth's gravity. Therefore, at the lowest point, Tarzan's acceleration is zero.