Which statement about positive reinforcers is true?

The statement that a positive reinforcer increases the likelihood of a behavior being repeated is correct because this concept is fundamental to operant conditioning in animal training. When a positive reinforcer, such as treats, praise, or toys, is presented to a dog immediately following a desired behavior, it reinforces that behavior and makes it more likely to be repeated in the future. This reinforcement works by creating a favorable consequence for the dog, which encourages it to perform the same behavior again to achieve the same reward.

The other options do not encapsulate the definition of positive reinforcement as accurately. While positive reinforcers can indeed enhance the training relationship and can be preferable to negative reinforcement, these aspects are not universally true for all situations. Additionally, not all positive reinforcers must be food, as they can take various forms that are meaningful to the individual dog. The essence of positive reinforcement lies in its effectiveness in modifying behavior through rewards, which is why the statement about increasing behavior likelihood is foundational and universally applicable.