Complex sentence: DC's Captain Comet and Tempest I were initially described as being mutants, and the the Justice League Unlimited episode "Fearful Symmetry", explicitly references both Mutants and Metahumans in a single sentence.
Split into simpler sentences: DC's Captain Comet and Tempest I were initially described as being mutants. In the televised DCU, the the Justice League Unlimited episode "Fearful Symmetry" explicitly references both Mutants and Metahumans in a single sentence.