Why must the cells of multicellular organisms differentiate

Multicellular organisms are more complex and it the organism such as a human did not differentiate the cells would not be able to compensate for all the functions that the body has developed through evolution

I think because they need to have variation plus it is not just a must but because multi-cellular organisms are sexual reproduction not asexual reproduction it allows for variation.

Control variable- changedependant variable- stays the samechanging- food itemsdependant- presences of proteins

Answer : romans built laws to manage the pollution which was lead by smoke produced by the factories.

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.