The cells responsible for transporting oxygen throughout the body are red blood cells, also known as erythrocytes.

Here's why:

* Hemoglobin: Red blood cells contain a protein called hemoglobin. Hemoglobin binds to oxygen in the lungs, forming oxyhemoglobin. This oxygen-rich blood then circulates throughout the body.

* Shape and Structure: Red blood cells are small and biconcave (disk-shaped with a depression in the center), which increases their surface area for oxygen absorption and allows them to easily pass through capillaries.

* No Nucleus: Unlike most other cells, red blood cells lack a nucleus, which increases their space for carrying oxygen.

While other cells and systems play a role in respiration (like the lungs and heart), red blood cells are the primary transporters of oxygen in the body.