Answer:
melanin affects how one looks (1st question)
cause and effect (2nd question)
Explanation:
for the 2nd question, its cause and effect because uv rays hit our skin and our skin is affected which gives us suntan.
It would be Primary because the lake is it’s starting point and the pollution grew all the way to the factory.
Viruses need to be inside a living thing (of course the living thing has to have the right temperature which most living things do) . When they're inside a living thing they start injecting the host's cells with its DNA in order to make more copies of itself which allows the virus to spread. So basically viruses need to be inside something living.
