Einstein's Principle of Equivalence in His General Theory of Relativity

Einstein's principle of equivalence in his general theory of relativity asserts that:

A) the behavior of all types of atoms in a gravitational field is equivalent.
B) all objects are attracted toward all other objects in the universe by gravitational forces.
C) being at rest in a gravitational field is equivalent to being in an upwardly accelerated frame of reference in a gravity-free environment.
D) if person B is in a rapidly moving reference frame (moving at constant velocity) , then person B will observe exactly the same effects for person A as person A observes for person