Answer:
B. the body's internal environment
Step-by-step explanation:
Homeostasis is defined as the process of maintaining the internal environment of the body.
All the systems work together to maintain homeostasis. The nervous and endocrine systems are two important system that helps in maintaining homeostasis.
The nervous and endocrine systems are linked with hypothalamus that controls the internal environment of the body by releasing and inhibiting hormones. These hormones keep pH, temperature, and other internal conditions stable that support homeostasis.
Hence, the correct answer is "B. the body's internal environment".