The term balanced polymorphism refers to $$

a state in which recessive and dominant alleles are found at equal proportions of $0\mathrm{.}5$ and $0\mathrm{.}5$ in a population

a state in which a deleterious allele exists at a frequency above that predicted by mutation$-$selection equilibrium due to a fitness advantage in the heterozygote

a balance between the poly and the morphism in a population under stabilizing selection

None of the above