An object in equilibrium has no NET force acting on it. It's acceleration is zero, meaning that it's moving in a straight line with constant speed (which may be zero).
Galaxies are comprised of groups of stars circling a common gravitational point (which is theorized in the Milky Ways case to be a black hole). The answer is True.
D. Circulatory
The digestive system works very closely with the circulatory system to get the absorbed nutrients distributed through your body. The circulatory system also carries chemical signals from your endocrine system that control the speed of digestion.
B. In the system of the object and the earth, by Newton's third law, the object will exert and equal and opposite force upon the earth.
Formally stated, Newton's third law is: For every action, there is an equal and opposite reaction. The statement means that in every interaction, there is a pair of forces acting on the two interacting objects.