<span>D: Viruses
I hope helped ^-^</span>
I would go on on the first option, population, community, ecosystem. If there is a control on the rapid growth of population, surely, pollution in the whole community will be reduced thus, making the ecosystem well balanced.
Answer:
The mass number is the sum of protons and neutrons. This means to find the number of neutrons you subtract the number of protons from the mass number. On the periodic table, the atomic number is the number of protons, and the atomic mass is the mass number.
