Which sentence below most effectively combines the two following sentences?

(1) he has an acute sense of hearing. (2) this enables him to climb by listening to the footsteps of his companions and to a bell tied to the climber ahead of him.

he has an acute sense of hearing, this enables him to climb by listening to the footsteps of his

companions and to a bell tied to the climber ahead of him.

he uses his acute sense of hearing to climb by listening to the footsteps of his companions and to

listen for a bell tied to the climber ahead of him.

he uses his acute sense of hearing, while climbing by listening to the footsteps of his companions

and to a bell tied to the climber ahead of him.

he has an acute sense of hearing, which enables him to climb by listening to the footsteps of his

companions and to a bell tied to the climber ahead of him.

*i think it is b*