The Reaction, Where En Represents Ethylenediamine, Has a Small $\Delta$

The reaction, where en represents ethylenediamine, has a small value for the enthalpy change, $\Delta$ H_rxn, yet the equilibrium constant for this reaction is large because

A) the reaction rate is fast.
B) the entropy change is large and positive.
C) the enthalpy change is large enough to matter.
D) the entropy change is large and negative.
E) the equilibrium constant does not depend on the enthalpy change.