Answer:
Sorry mate! I can't understand this language...
Answer: A. Pollutants
Explanation:
"A pollutant is a substance or energy introduced into the environment that has undesired effects, or adversely affects the usefulness of a resource. ..." - Wikipedia
Helium,it has an atomic mass of 4,which means total no. of protons and neutrons,so I think you meant 2 protons and an atomic mass of 4
Your answer would be D, single replacement