The Hexaammine Cobalt(III)ion Is Very Unstable in Acidic Aqueous Solution

The hexaammine cobalt(III) ion is very unstable in acidic aqueous solution: [Co(NH₃) ₆]³⁺(aq) + 6 H₃O⁺(aq) → [Co(H₂O) ₆]⁴⁺(aq) + 6 NH₄⁺(aq)
However,solutions of hexaammine cobalt(III) can be stored in acidic solution for months without noticeable decomposition.Which statement below about the equilibrium constant and the activation energy for the reaction is true?

A) K_eq < 10³ and E_a is very small.
B) K_eq > 10³ and E_a is very small.
C) K_eq < 10³ and E_a is very large.
D) K_eq > 10³ and E_a is very large.