The abdominal segments of Drosophila have no appendages. Loss of function of bithorax genes results in appendages forming in these abdominal segments. Therefore, ________.
◦ bithorax mutations are necessarily recessive
◦ bithorax genes normally activate appendage-forming genes
◦ ultrabithorax usually acts to oppose bithorax genes
◦ bithorax normally activates a gene that negatively regulates appendages in the abdomen
◦ expression of bithorax wild-type genes suppresses all appendage formation