The articular cartilage that forms a rim around the hip joint socket is called the:

The correct answer is: The septum.

Explanation:

The hip joint is an articulation that unites the pelvis with the femur.

A septum is a cartilage wall which has the purpose or the function to divide a particular cavity into smaller ones.

There are multiple septums in the human body, such as the interatrial septum, which is located in the left and right atria of the heart and the nasal septum which is the wall that separates the nostrils of the nose.

In conclusion, the articular cartilage that forms a rim around the hip joint socker is called the: Septum.