Salivary amylase beings the digestion of which nutrient in the mouth?
a. protein
b. fat
c. carbohydrate
d. iron

C. carbohydrate.

Explanation:

The digestion of carbohydrate starts in the mouth, where the salivary amylase converts carbohydrate in the food to maltose. This action continues through the esophagus, and when it gets to the stomach, it stops due to the acidic nature of the stomach (as the amylase works only in alkaline environment).

The maltose (disaccharides) is further broken down to monosaccharides called glucose in the duodenum. other disaccharides like sucrose and lactose are coverted to glucose + fruitose by sucrase, and glucose + galactose by lactase respectively. Carbohydrate in the duodenum are broken down to maltose by pancreatic amylase before converted to glucose.

they had the law tat factories that produces smoke cannot be built near residential buildings.

building of proper sewage system was done to ensure that the waste is carried away from the humans so that they do not get diseases from it.

also they built water systems to provide water in those areas which are drought prone.