Answer:
a. lowering the center of gravity.
Explanation:
A stable body is the one that experiences a net force in the direction opposite the direction of displacement. A body that is stable has a restoring force that restores it to the original equilibrium position. Many factors helps to increase stability, and one of them is lowering the center of gravity closer to the ground. This is why race cars are closer to the ground, to give them more stability especially at high speed.