The correct answer is "thoracic duct".
The thoracic duct (also called as the left lymphatic duct or the alimentary duct) is the structure wherein most of the lymph in the drained from the lymphatic vessels goes to this structure. In the thoracic duct, lymph flows up to the level of the brachiocephalic vein where lymph returns to the venous circulation.
C. testable and observable
The word biology comes from the Greek word <em>bios</em>, meaning life, and <em>logos</em>, meaning study.
