The correct option is D Lumen of intestine
The septal nephridia of the earthworm are the largest and are situated in four rows on the intersegmental septa in each segment behind the fifteenth. The terminal duct of septal nephridium is a short tube and many ducts open into a pair of septal excretory ducts situated along the septum in each segment. The septal excretory duct open and pour their contents into a pair of supraintestinal excretory duct. These longitudinal excretory ducts open into the lumen of the intestine. So, the correct answer is option D.