Joan has been working in a bicycle factory for several months. The assembly process requires multiple tasks, and Joan's supervisor assigns her to apply the custom paint and add the decals. Adding the decals requires perfection, and Joan does it quickly and always performs the task well, so her supervisor decides to keep her in this position. This is an example of

a$.$ standard operating procedures.

b$.$ time$-$and$-$motion study.

c$.$ job specialization.

d$.$ the human relations movement.

e$.$ job rotation.