Which of the following structures is part of the lower respiratory tract?

• A. Oral cavity
• B. Trachea
• C. Nasal cavity
• D. Pharynx

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the division of the respiratory tract into two main parts: the upper respiratory tract and the lower respiratory tract. The upper respiratory tract includes structures such as the nasal cavity, oral cavity, and pharynx, while the lower respiratory tract includes structures such as the trachea, bronchi, and lungs.
2. Step 2: Review the anatomical location and function of each structure listed in the problem. The nasal cavity and oral cavity are involved in air intake and are part of the upper respiratory tract. The pharynx serves as a passageway for air and food and is also part of the upper respiratory tract.
3. Step 3: Focus on the trachea. The trachea is a tube-like structure that connects the larynx to the bronchi and serves as a passageway for air to reach the lungs. It is located below the larynx and is part of the lower respiratory tract.
4. Step 4: Compare the listed structures to determine which one belongs to the lower respiratory tract. Based on anatomical classification, the trachea is the correct answer as it is part of the lower respiratory tract.
5. Step 5: Conclude that the trachea is the correct answer because it is anatomically classified as part of the lower respiratory tract, while the other structures listed (oral cavity, nasal cavity, and pharynx) are part of the upper respiratory tract.