What describes a concurrent schedule of reinforcement?

A concurrent schedule of reinforcement is characterized by the presence of two or more independent reinforcement contingencies available to the individual at the same time. This means that the individual can choose between different behaviors, each of which may lead to a different reinforcer. For example, if a person can earn a reward through engaging in either behavior A or behavior B, they are faced with a choice that reflects a concurrent schedule. This setup allows for the analysis of preference and choice-making behavior, as the individual may select the option that yields the most desirable outcome.

The other choices describe different aspects of reinforcement schedules but do not accurately capture the essence of concurrent schedules. Some may refer to single behaviors receiving multiple reinforcers or involve alternating schedules, but they do not reflect the independent availability of multiple reinforcement contingencies that defines a concurrent schedule.