Which of the following is part of the appendicular skeleton?

The appendicular skeleton is primarily composed of the bones of the limbs and their connecting girdles. This includes the bones of the upper limbs (such as the arms, forearms, wrists, and hands) and the bones of the lower limbs (such as the thighs, legs, ankles, and feet). The term "appendicular" specifically refers to these appendages as they are attached to the axial skeleton, which consists of the central core of the body, including the skull, ribcage, and vertebrae. Therefore, limbs are indeed part of the appendicular skeleton, making this the correct answer.

In contrast, the skull, ribcage, and vertebrae belong to the axial skeleton, which provides the main framework supporting the body's structure and protecting vital organs.