Because urine,animal dung and vegetable wastes are the wastes from animals, kitchen and toilets.These wastes are ORGANIC so option c is right.

Inorganic Impurities Present in Sewage
There are various inorganic impurities that can be present in sewage. Among the options provided, the correct answer is C: metals. Here is a detailed explanation of the inorganic impurities present in sewage:
1. Metals:
- Sewage can contain various metals, both naturally occurring and those introduced through human activities. Some common metals found in sewage include lead, mercury, cadmium, copper, zinc, and chromium.
- These metals can enter the sewage system through industrial discharges, stormwater runoff, and domestic wastewater.
- Metals in sewage can have harmful effects on the environment and human health if not properly treated before discharge.
2. Urine:
- Urine is not considered an inorganic impurity but rather an organic component of wastewater.
- It contains various organic compounds, including urea, ammonia, and other nitrogenous compounds.
- While urine can contribute to the overall composition of sewage, it is not classified as an inorganic impurity.
3. Animal Dung:
- Animal dung is also not considered an inorganic impurity but rather an organic component of sewage.
- It contains organic matter, including feces and undigested food.
- While animal dung can be a source of organic pollutants in sewage, it is not classified as an inorganic impurity.
4. Vegetable Wastes:
- Vegetable wastes, similar to animal dung, are organic components of sewage.
- They consist of plant materials, such as leftover fruits, vegetables, and their peels.
- While vegetable wastes can contribute to the organic load of sewage, they are not classified as inorganic impurities.
In conclusion, among the given options, the inorganic impurities present in sewage are metals. It is important to properly treat sewage before its discharge to minimize the harmful effects of these impurities on the environment and public health.