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

Answer:

D. the spinal cord

Brief Explanation:

Reflex actions are mainly coordinated by the spinal cord. It can process and respond to stimuli without involving the brain in some simple reflex - arc pathways. The heart is mainly for circulation, the brain - stem has other vital functions like regulating basic life - sustaining processes, and the vertebral column protects the spinal cord but is not directly involved in the reflex action mechanism.