The path of water in a sponge is:

• A
  Dermal ostia $\to$ Gastral ostia $\to$ Osculum
• B
  Dermal ostia $\to$ Gastral ostia $\to$ Spongocoel $\to$ Osculum
• C
  Osculum $\to$ Spongocoel $\to$ Choanocytes $\to$ Ostia
• D
  Pinacocytes $\to$ Choanocytes $\to$ Enteron $\to$ Osculum