The consequences of uneven water distribution include ( ) A: "mud ball" or "mud cake" will form, which can cause a short-circuiting phenomenon during filtration B: the filter media may break during filtration and backwash periods C: backwash pipes may be destroyed D: The particles of the local support layer will move and mix with the filter media, and the filter media will run off under this situation if a large amount of uneven backwash water come through