3. Cells for growth and repair
A Cells for sexual ronroduction
Is it mitosis or meiosis

b. the carbon cycle ensures living things have a source of hydrogen

a physical change is being made.

instead of copying and pasting things off of tests or work done on computer which im sure you did, try and read over the question carefully

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.