Entropy by the modern definition is the amount of energy dispersal in a system. Therefore, the system entropy will increase when the amount of motion within the system increases. For example, the entropy increases when ice (solid) melts to give water (liquid). It will even increase more when water is evaporated to steam (gas).
(from wiki)
An object with more mass has more kinetic energy than an object with less mass, if both objects are moving at the same speed. <em>(c)</em>
When we're working problems that involve a pendulum, we almost always IGNORE anything else besides gravity.
Anything else besides gravity that could influence the motion of a pendulum is something that we would eliminate if we could.
Those are air resistance, mass of the string, friction at the top suspension point, and the Coriolis force, due to the Earth's rotation, that tries to change the plane of the pendulum's swing.
This question is probably fishing for the answer "<em>friction</em>".