Answer:
Reflex.
Explanation:
In psychology and medicine, a reflex is a muscle reaction that happens in an automatic way as a response to an stimuli.
Babies are born with some reflexes (as some kind of survival skills) and they start disappearing as they grow older. It is important to know the typical age for a reflex to disappear because the fact that some reflexes persists after some age can be a sign of problems in the neurological development or brain damage.
One of these infant reflexes is the one that make infants move their arms and legs in swimming movements when submerge in the water.
In this example, Jayden instinctively held his breath and moved his arms and legs in swimming movements when she was dropped in one end of the pool. This was an automatic reaction that took place as a response to water. Therefore, this is an example of a reflex.