The reaction of an olefin with $$\mathrm{HBr}$$ can proceed by ionic as well as radical mechanism. The reaction in the presence of light takes place by radical mechanism, as

A

the free energy of the reaction in radical mechanism is higher than in ionic mechanism

B

ionic mechanism requires a catalyst while radical mechanism does not

C

in the presence of light the activation energy of the reaction is lower than that for ionic mechanism

D

a radical reaction has very low activation energy as compared to that for the corresponding ionic reaction