Answer:
A. a reflex.
Step-by-step explanation:
Reflex is an involuntary and instantaneous movement in response to a change in environment. Movement of hand away from hot or cold body and Coughing or sneezing etc are the examples of reflex actions. Reflex actions are involuntary which means can not be control by human body. These actions are present in every individual from its birth and unlearned which work automatically in the body.