Final answer:
Pharyngeal slits are indeed commonly referred to as gill slits, especially concerning their role in the embryonic development of vertebrates and their specialized functions in fish. The correct option is true.
Step-by-step explanation:
Pharyngeal slits, also referred to as gill slits, are openings located in the pharynx, just behind the mouth, that communicate with the external environment. In aquatic organisms, pharyngeal slits facilitate the exit of water that is taken in during feeding. In some invertebrate chordates, they help to filter food from the water. For vertebrate fishes, the slits adapt to support the gills, and in jawed fishes, they support the jaws. In tetrapods - which includes amphibians, reptiles, birds, and mammals - these structures are highly modified and no longer function as gill supports, but instead form parts of the ear, tonsils, and thymus gland. Thus, the statement 'Pharyngeal slits may also be called gill slits' is True when considering the embryonic development of vertebrates and the functional adaptions in fishes.