\begin{tabular}{l} 3. If your instructor asked you to compare the structure of the upper and \\ lower extremities, which of the following might you say? \\ a. The upper and lower extremities have a similar structure, with a large \\ bone articulating with two smaller bones via a joint. \\ b. There are no similarities in the structures of the upper and lower \\ extremities. \\ c. Both the upper and lower extremities are divided into two regions. \\ d. Both the upper and lower extremities are divided into four regions. \\ \hline\end{tabular}

To compare the structure of the upper and lower extremities, let's analyze the options provided: 1. **Option a**: "The upper and lower extremities have a similar structure, with a large bone articulating with two smaller bones via a joint." - This statement is true for both extremities. For example, in the upper extremity, the humerus (large bone) articulates with the radius and ulna (smaller bones) at the elbow joint. Similarly, in the lower extremity, the femur (large bone) articulates with the tibia and fibula (smaller bones) at the knee joint. 2. **Option b**: "There are no similarities in the structures of the upper and lower extremities." - This statement is false. As noted in option a, there are indeed structural similarities between the two. 3. **Option c**: "Both the upper and lower extremities are divided into two regions." - This statement is misleading. The upper extremity is typically divided into three regions: the arm, forearm, and hand. The lower extremity is also divided into three regions: the thigh, leg, and foot. 4. **Option d**: "Both the upper and lower extremities are divided into four regions." - This statement is also incorrect. As mentioned, both extremities are generally divided into three regions. Based on this analysis, the most accurate statement is **Option a**. The upper and lower extremities do share a similar structural design, with a large bone articulating with two smaller bones via a joint.