3. If a chemical reaction begins with 4 carbon atoms and 8 hydrogen atoms in the reactants, according to the Law of Conservation of Mass how many carbon atoms and hydrogen atoms need to be present on the product side?​

what is this saying?

answer denitrification;

the right option is; decreased genetic variation  

decreased genetic variation describes the effect of this environmental change.

genetic variation is the naturally occurring genetic diversities or differences between organisms of the same species in a population. genetic variation allows the survival and adaptability of a species when they encounter changing environmental conditions. when an endangered species reduces, it loses genetic variation which may not be restored even if the species rebound and will only be recovered through the gradual collection of mutations over many years.