The body's ability to maintain a relatively constant internal environment is called homeostasis. this stability can be challenged by(there can be more than one answer)
reduced water or food intake
infectious organisms.
elevated or depressed blood ph
extreme temperatures.

Homeostasis can be defined as the state of maintenance of the constant internal conditions by the living organisms. The homeostasis is maintained by the body so that it may function properly. The homeostasis will be disturbed by the reduced intake of the food and water. Healthy intake of water and food is essential in maintaining the homeostasis of the body. The elevated or depressed blood pH along with extreme body temperatures will also disturb the homeostasis of the body making the person sick. Moreover, certain infectious organisms also alters the homeostasis of the body.

Hence, all the options are correct.

All options are correct

Explanation:

Homeostasis is the ability of body to maintain stable internal environment. This is possible only when all the internal body organs and systems are performing well. In order to achieve such conditions, all functions are to be maintained at cellular level such as food ingestion, digestion, excretion, material exchange, reproduction, obtaining energy from mitochondria etc.  

If any of these functions is destabilized at cellular level due to change in external environment, then the overall internal stability of the body will get destabilized.  

Hence,  all the options are correct