Which of the following contributes to maintaining homeostasis in the body?

Maintaining homeostasis in the body involves a complex interplay of various systems, particularly those involved in regulation and balance. The excretory system plays a crucial role in homeostasis by managing the removal of waste products and excess substances from the body, such as water, salts, and toxins, which helps control internal fluid levels and maintain electrolyte balance.

Similarly, the endocrine system is vital for homeostasis as it regulates physiological processes through hormones. These hormones control various functions, including metabolism, growth, and response to stress, thereby influencing temperature regulation, blood pressure, and hydration levels.

Both the excretory and endocrine systems work together to ensure that the body's internal environment remains stable despite external changes. While other systems, such as the skeletal system, have important functions, they do not directly contribute to the regulation needed for homeostasis in the same way as the excretory and endocrine systems. Therefore, the correct response focuses on the essential roles that both the excretory and endocrine systems play in maintaining the body's internal balance.