The allylic hydrogen of cyclopentene is more easily abstracted than the secondary hydrogen of cyclopentane because the former produces an allylic radical stabilized by resonance, which is less stable than the secondary radical produced by the latter.

The allylic hydrogen of cyclopentene is more easily abstracted than the tertiary hydrogen of cyclopentane because the former produces an allylic radical stabilized by resonance, which is less stable than the tertiary radical produced by the latter.

The allylic hydrogen of cyclopentene is more easily abstracted than the secondary hydrogen of cyclopentane because the former produces an allylic radical stabilized by resonance, which is much more stable than the secondary radical produced by the latter.

The allylic hydrogen of cyclopentene is more easily abstracted than the secondary hydrogen of cyclopentane because the former produces an allylic radical stabilized by induction, which is much more stable than the secondary radical produced by the latter.