The correct option is D Fallopian tube
The paired fallopian tubes are small ducts, that transport the ovum from the ovaries to the uterus. In rats, the cranial end of each tube forms a capsule that completely encloses the ovary. In rats, the fertilization is internal and it takes place in the uppermost portion of the fallopian tube, which is dilated.
So, the correct answer is option D.