which structure is at work when the body deals with reflex actions?\nthe heart\nthe brain stem\nthe…

Brief Explanations:

Reflex actions are involuntary responses. The spinal cord is responsible for simple reflexes. It can process and respond to stimuli without involving the brain in some cases. The heart is for circulation, the brain - stem has other vital functions (like regulating breathing, heart rate), and the vertebral column is a protective structure.

Answer:

the spinal cord