I need help please and thank you

lipid

Explanation:

lipids form phospholipid bilayers which are the largest portion of the cell membrane and contain a hydrophobic (insoluble in water) end made up of two fatty acid chains of nonpolar molecules such as carbons and hydrogens. The other end is hydrophilic (soluble in water) and contains polar phosphate molecules.

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.