Could Social and Solitary Phenotypes Ever Occur in the Same

Could social and solitary phenotypes ever occur in the same species strictly because of environmental differences that affected the development of the two phenotypes?

A) No, because both genetic and environmental factors are necessary for development of every phenotype.
B) No, because this is equivalent to saying that the two traits are environmentally determined, which is incorrect.
C) Yes, because as polyphenisms illustrate, some differences in gene-environment interactions are caused only by differences in the environment side of the interaction.
D) Yes, because the environment is absolutely essential for the development of every phenotype, especially behavioral ones.