The product obtained when propene undergoes an addition reaction with $\mathrm{HBr}$ in the presence of benzoyl peroxide is

When the addition of haloacid takes place the reaction does not follow markonikoffs rule and the phenomenon is called khrash effect. This can be depicted on propene as

Here 1-bromo-propane is major due to the presence of peroxide which reverses the markonikoffs rule by stabilizing 1-degree product.

Hence option A is the correct answer.