Answer:
C. asteroid is large enough to create a gravitational force that is strong enough.
Explanation:
Basically all celestial bodies are subject to Gravity among them, so the rules of gravity apply for the strongest to the smallest, the strongest attract the weakers into their orbit, so an asteriod can have a moon since a moon it´s just a weaker celestial body with a weaker gravity force that is attracted towards another bigger celestial body. An asteriod just would have to find a celestial body with a weaker gravity force and strong enough to endure traveling alongside the asteriod.
