In the context of training methods, which of the following is a difference between on$-$the$-$job training and role$-$playing?

a$.$ On$-$the$-$job training is specifically used when the training objective is to develop analytical and personality skills, whereas role$-$playing is usually used when the training objective is to impart knowledge to trainees.

b$.$ In on$-$the$-$job training, trainees learn by watching experienced employees perform their job and eventually by working alongside the experienced employees, whereas in role$-$playing, trainees practice new behaviors by acting out what they would do in job$-$related situations.

c$.$ On$-$the$-$job training requires organizations to hire skilled trainers, whereas role$-$playing does not involve trainers.

d$.$ In on$-$the$-$job training, top$-$level managers give informal advice and suggestions to trainees, whereas in role$-$playing, mentors guide trainees through live tasks.