What body part is typically classified as an extremity in humans?

The arm is classified as an extremity in humans because it is one of the two primary appendages extending from the body. Extremities refer to the limbs or appendages, which in human anatomy include the upper limbs (arms) and lower limbs (legs). The classification is based on their functional role in mobility and manipulation, as well as their anatomical position relative to the torso.

In contrast, the stomach, chest, and back are considered central or core parts of the body rather than extremities. The stomach is primarily an organ involved in digestion, while the chest is a region containing vital organs such as the heart and lungs, and the back provides structural support and protection for the spinal cord. Therefore, the arm stands out as the correct answer due to its role as a limb, distinguishing it from the other options that relate to the central core of the body.