the body's ongoing process of regulating its internal environment-electrolyte balance, blood chemistry, temperature, and so on-is called

a. excretion
b. metabolism
c. homeostasis
d. peristalsis

Metabolism

The correct answer is c. homeostasis.

To arrive at this answer, we need to understand the definitions of the given options and match them with the process described in the question.

a. Excretion is the process of eliminating waste products from the body, such as urine from the kidneys or carbon dioxide from the lungs. It does not involve regulating the internal environment.

b. Metabolism refers to all the chemical reactions that occur within the body to maintain life and support various functions like energy production, growth, and repair. While metabolism is essential for maintaining homeostasis, it does not specifically refer to the ongoing regulation of the internal environment.

c. Homeostasis is the body's ability to maintain a stable internal environment despite external changes. It involves the regulation of various parameters such as electrolyte balance, blood chemistry (pH, oxygen, etc.), body temperature, and many other factors. Homeostasis ensures that the body functions within narrow limits, allowing cells and organs to carry out their necessary processes efficiently.

d. Peristalsis is the muscular contraction and relaxation that propels food along the digestive tract. Although it is an important function of the body, it does not encompass the overall regulation of the internal environment as described in the question.

Therefore, the correct answer is c. homeostasis.