To Prevent Taking Back in the Wastes It Has Just

To prevent taking back in the wastes it has just expelled,a standard sediment-inhabiting bivalve mollusk should position itself

A) with the incurrent siphon upstream.
B) with the excurrent siphon upstream.
C) in any direction,since it can control which way the water flows in either siphon.
D) either with the incurrent siphon upstream or with the excurrent siphon upstream,but not in any direction,since it can control which way the water flows in either siphon.
E) None of the choices is correct