Refer to the Diagram Below of a Countercurrent Exchanger from a Fish

Multiple Choice

Refer to the diagram below of a countercurrent exchanger from a fish gill. The values represent percent saturation of O₂. Based on this information alone, which of the following statements is true?

A) Tube AB represents the flow of water and tube CD represents the flow of blood.
B) Tube CD represents the flow of water and tube AB represents the flow of blood.
C) The fluid in tube AB flows from A to B.
D) The fluid in tube CD flows from D to C.
E) Both a and c