Fone possesses one allele for blood group a antigen and one allele for blood group b, he will have type ab blood, distinctly different from both a and b. this type of inheritance is called

Codominance

Explanation:

According to the given information, an individual carries one allele for blood group A antigen and one allele for the blood group B. Let's assume that the allele I^A imparts blood type "A" while the allele I^B is responsible for blood type B. Now, the genotype of the individual is I^AI^B and its phenotype is blood type "AB".

When both the alleles of a gene are expressed in a heterozygote and the phenotype of the heterozygote is distinct from both the pure breeding parents, the pattern of inheritance is called codominance. The I^A and I^B alleles codominant as both are equally expressed in the heterozygote.

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.