Although Adult Tunicates Are Stuck to the Ocean Bottom, They

Although adult tunicates are stuck to the ocean bottom, they are considered early relatives of vertebrates because

A) tunicate gill slits are like ribs.
B) tunicate adults have a notochord.
C) tunicate larvae have a notochord.
D) all vertebrate embryos go through a stage that resembles adult tunicates.
E) tunicate adults have all four chordate characteristics.