Final answer:
Baleen whales have genes for teeth because they are inherited from their toothed ancestors, not because they need them for baleen or future use, or due to evolution's inability to remove genes.
Step-by-step explanation:
Baleen whales still have genes for building teeth because their ancestors had teeth and they inherited these genes from them, even though the genes no longer function (option 2). The presence of these genes in baleen whales does not mean they are used to make baleen, nor does it suggest that evolution is keeping the genes around for possible use by descendants or because evolution cannot remove genes. Rather, these genes are part of their genetic heritage. Over the course of evolutionary history, many organisms retain vestigial genes and structures from their ancestors, even if they no longer serve their original purpose.
For instance, whales are descended from land-dwelling ancestors with fully developed limbs, yet modern whales have vestigial pelvic bones. This aligns with the process of evolution, where changes in species over time can include the reduction or loss of previously functional traits when they are no longer needed for survival. Moreover, mammals, including whales and dolphins, have adapted from land-dwelling creatures to life in the ocean, yet they retain some genetic features from their terrestrial origins.