Q: The superior vena cava and the inferior vena cava are veins that return blood lacking what to the heart?


Read this paragraph and choose the correct option from the provided answers:

The veins that return oxygen-poor blood to the heart are the superior vena cava and the inferior vena cava . The pulmonary veins return oxygen-rich blood from the lungs to the heart. The pulmonary veins are the only veins that carry oxygen-rich blood.

 Choices:

- hemoglobin

- carbon dioxide

- nitrogen

- oxygen


A:
oxygen