in Job __________ , employees are paid a given amount for each unit they produce, directly linking the amount they earn to their productivity.

A. Enlargement

B. Rotation

C. Enrichment

D. Sharing

I'm confused as to if it falls under enlargement or enrichment as most of the time they are used interchangeably. My text has the following which doesn't help either.

Job enlargement - increases the number and variety of tasks an employee performs

Job enrichment - is a vertical expansion of the employees job which gives increased decision making responsibilities along with more autonomy.

Job rotation - shifts employees from job to job within the organization to promote growth for and build skills/ abilities