Taking the Zero of Potential Energy to Be at the Infinite

Multiple Choice

Taking the zero of potential energy to be at the infinite separation of two masses,consider the energy of a body in circular planetary motion.Which of the following statements is valid?

A) The total mechanical energy of the system is constant and negative.
B) The total mechanical energy of the system is constant and positive.
C) The potential energy of the system is equal to the kinetic energy but opposite in sign.
D) The potential energy of the system decreases as the radius of the orbit increases.
E) None of these is valid.