Natural selection works on the phenotype, rather than genotype, what best explains the reason for this

Genes aren't eradicated from natural selection, but the chances of getting the phenotypes (the physical attributes of an organism based on the genes) go down as the organisms with those phenotypes die out.

Explanation:

Recessive genes are still present in, for example, a heterozygous genotype. but since there is a dominant, it covers the recessive gene and the phenotype won't have anything to do with the recessive gene (unless we are talking about incomplete or codominance).

the menstrual cycle – higher tier. negative feedback mechanisms affect the production of hormones in the menstrual cycle. oestrogen also stimulates the release of lh (luteinising hormone) from the pituitary gland, which in turn controls the production of progesterone.

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.