Teaching assistants are paid a meager sum of money once a month, whether they work hard or not. This type of payment plan demonstrates a reinforcement schedule.

The correct answer is letter "B": fixed-interval.

Explanation:

American psychologist and social philosopher B.F. Skinner (1904-1990) is the father of Operant Conditioning Theory which proposes it is needless to analyze thoughts to explain individuals' behaviors. In such a way, Skinner believed human beings react based on a series of rewards and punishments influenced by reinforcements.

Skinner schemed five (5) schedules to relate the nature of those reinforcements: continuos, fixed-interval, variable interval, fixed ratio, variable ratio.  In the fixed-interval rewards are given at fixed rates. This causes average and irregular performance with rapid extinction. Thus, a payment plan that does not vary based on performance is an example of the fixed-interval reinforcement schedule.

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