Concept:The ability of an organism to keep its internal environment stable despite changing external conditions.
Explanation:Living organisms constantly face changes in temperature, water level, pH, and other factors.
Homeostasis is the process that regulates these conditions to maintain a steady, balanced internal environment.
This process covers temperature control, water balance, and many other body functions.
Osmoregulation deals only with water and salt balance, so it is a narrower process.
Equilibration is a physical term, and plasmolysis is the shrinking of plant cells due to water loss.
Hence, the broad process described in the question is homeostasis.
Answer:C. homeostasis