7. The rate constant for the gas-phase decomposition of N2O5, N2O5 → 2NO2 + (1/2)O2 has the following temperature dependence:k (s-1) = 4.9 × 10-3 at 338 K, 5.0 × 10-4at 318 K, and 3.5 × 10-5at 298 K. The activation energy for the reaction is_________ kJ/mol. 
(A) 91.5
(B) 186
(C)100
(D) 19
(E)139