Question

researchers have discovered that the ear bones of mammals are homologous to some bones in fish jaws. which claim is best supported
selection pressures have acted over time on mammals but not fish.
selection pressures have promoted similar evolution in fish and mammals.
fish do not require a sense of sound.
fish and mammals have a distant common ancestor.

Explanation:

Homologous structures indicate a common evolutionary origin. If mammalian ear bones are homologous to some fish jaw bones, it implies that fish and mammals share a distant common ancestor from which these structures evolved. Selection pressures act on all species (so the claim about only acting on mammals is wrong). Fish do have a sense of sound (they can detect vibrations). Similar evolution (convergent evolution) would lead to analogous not homologous structures.

Answer:

Fish and mammals have a distant common ancestor.