A Racehorse Cannot Stand on One Leg, but When It

Multiple Choice

A racehorse cannot stand on one leg, but when it runs it rarely has more than one leg on the ground. Why is a running horse more stable than a standing one?

A) Its legs tilt so the hooves fall in line with its center of gravity.
B) Its momentum gives it stability.
C) Its internal organs act like a gyroscope.
D) It uses its neck for balance the way a tightrope walker uses a pole.