`CH_(3)-CH_(2)-underset(CH_(3))underset(|)(C)H-Cl` is more reactive.
Because secondary carbocation formed in the slow step is more stable as compared to the primary carbocation in the other reaction.
Correct Answer - B
`CH_(3)-underset(D)underset(|)((C)H-underset(CH_(3))underset(|)overset(**)(C)-CH_(3)` (tertiary free radical) is maximum. Stable due to hyperconfiguration.