Because in cities there is more air pollution going on making the water like rain more acidic. Buildings away from cities have less pollution.
By option A cell division.
The question is asking to state the substance that come from the outside in the process of photosynthesis, base on my research and further investigation, I would say that its the heat or light energy. I hope you are satisfied with my answer and feel free to ask for more
C, hydrogen bonds , i did this test last year and im in chemistry now, so its hydrogen bonds.
