Final answer:
The presence of ketones in the urine indicates that the body is using fat as an energy source instead of glucose. This can be seen in conditions like diabetes mellitus or severe protein/carbohydrate deficiency in the diet. The option (C) is correct.
Step-by-step explanation:
Finding ketones in the urine suggests that the body is using fat as an energy source in preference to glucose. In diabetes mellitus when there is not enough insulin (type I diabetes mellitus) or because of insulin resistance (type II diabetes mellitus), there is plenty of glucose, but without the action of insulin, the cells cannot take it up, so it remains in the bloodstream.
Instead, the cells are forced to use fat as their energy source and fat consumed at such a level produces excessive ketones as byproducts. These excess ketones will appear in the urine. Ketones may also appear if there is a severe deficiency of proteins or carbohydrates in the diet. Therefore, option (C) is correct.