Identify the vein that is circled in the image below (the one that is going slightly diagonally across the elbow area). Fill in the blank

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Correct answer: Superior vena cava (SVC)

The SVC is the large vein that returns venous blood from the head, neck and upper limbs into the superior aspect of the right atrium; anatomically it appears as the large trunk entering the upper right side of the heart in chest models.

A. Bronchomediastinal duct and subclavian duct: bronchomediastinal and subclavian are lymphatic trunks, not the two major collecting ducts.
B. Right and left thoracic ducts: there is a single thoracic duct (left-sided) and a separate right lymphatic duct; we do not have distinct “right and left thoracic ducts.”
C. Thoracic duct and right lymphatic duct: the thoracic duct drains most of the body into the left subclavian vein, and the right lymphatic duct drains the right head/neck, right upper limb, and right thorax into the right subclavian vein.
D. Lumbar duct and left lymphatic duct: “lumbar duct” is not a collecting duct term used in this context, and “left lymphatic duct” is another name sometimes used for the thoracic duct but paired with “lumbar duct” is not the standard two-collector pair.