During Countercurrent Flow Which Direction Does Water and the Blood

During countercurrent flow which direction does water and the blood flow?

A) Water flows out of the gills while blood flows in the opposite direction
B) Water flows in through the gills while blood flows in the opposite direction
C) Water flows out of the gills while blood flows in the same direction
D) Water flows inward across the gills while blood flows in the same direction
E) Water flows across the surface of the lungs while blood flows in the opposite direction