The reaction, 2 Cl 2 O(g) 2 Cl 2 (g) + O 2 (g) r

The reaction, 2 Cl₂O(g) → 2 Cl₂(g) + O₂(g) Δ_rH° = -161 kJ mol^-1, is expected to be 

(a) Spontaneous at all temperatures; 

(b) Spontaneous at low temperatures, but nonspontaneous at high temperatures;

(c) Nonspontaneous at all temperatures; 

(d) Spontaneous at high temperatures only.