Final answer:
The endocrine system is responsible for regulating the body's internal environment, including temperature and pH. c) Endocrine system
Step-by-step explanation:
The body system responsible for regulating the body's internal environment, including temperature and pH, is the endocrine system. The endocrine system secretes hormones that regulate various processes in the body, including temperature control and maintaining pH balance. For example, when the body temperature is too high, the endocrine system releases hormones that trigger sweating to cool down the body.