The members of the annelid class ( ) are considered closest to the ancestral annelid condition. A: Chaetognatha B: Gnathobdellida C: Polychaeta D: Oligochaeta E: Clitellata

Which phylum is characterized by pentameral symmetry (五辐射对称)? A: Mollusca B: Ctenophora C: Echinodermata D: Chaetognatha (毛颚动物门)