Why Are Inlets Through Barrier Bars or Barrier Islands Not

Why are inlets through barrier bars or barrier islands not closed by longshore drift of sand?

A) Such inlets are always the outlets for onshore rivers to reach the sea, so they flush the sand out.
B) Rapid flow of water back and forth through the inlet as tides rise and fall keeps it clear.
C) Longshore sand drifted into such inlets drops into deeper water, so it drifts out to sea.
D) Sand drifted into such inlets encounters brackish water from the inlet and dissolves.
E) Sand drifted into such inlets is carried into the lagoon by incoming waves.