Final answer:
An Incubator is the equipment used to regulate body temperature. It provides a controlled environment, unlike thermometers, stethoscopes, blood pressure cuffs, and syringes, which serve different purposes in medical settings.
Step-by-step explanation:
The piece of equipment used to regulate body temperature is D) Incubator. A thermometer (A) is used to measure temperature, not to regulate it. A stethoscope (B) is for listening to the internal sounds of the body, such as the heartbeat. A blood pressure cuff (C), often part of a sphygmomanometer, is used to measure blood pressure as depicted in the provided figures. A syringe (E) is a medical device used to inject or withdraw fluids but does not regulate temperature. An incubator, however, is specifically designed to maintain a controlled and often regulated environment for the purpose of caring for premature infants or cultivating microbiological cultures, which includes keeping the temperature at a constant, suitable level.