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

Brief Explanations:

Reflex actions are mainly coordinated by the spinal cord. It can process and respond to stimuli without the need for the brain to be fully involved in every step. The spinal cord acts as a relay - center for simple reflexes. The heart is mainly for circulation, the brain - stem is involved in vital life - functions like breathing and heart - rate regulation but not the main structure for reflexes, and the vertebral column protects the spinal cord but is not directly involved in the reflex action process.

Answer:

D. the spinal cord