Jayden's mother took him to a mother-infant swim class. When she dropped Jayden in the shallow end of the pool, she was surprised to see that he instinctively held his breath and moved his arms and legs in swimming movements. This is an example of a?

Bradycardic response.

Explanation:

The "diving reflex", or bradycardic response, is the natural reflex of infants on water, is an automatic response that they lose later in development, and it comes in order of survival mode and has an evolutionist logic.