How Is the Reaction Quotient Used to Determine Whether a System

How is the reaction quotient used to determine whether a system is at equilibrium?

A) The reaction is at equilibrium when Q > K_eq.
B) The reaction is at equilibrium when Q = K_eq.
C) The reaction quotient must be satisfied for equilibrium to be achieved.
D) The reaction is at equilibrium when Q < K_eq.
E) At equilibrium, the reaction quotient is undefined.