The Adam's apple is formed by the:

A. Allergic rhinitis is an allergic reaction to airborne particles like pollen or dust, and while it affects the upper respiratory system, it is not an infection.
B. COPD (Chronic Obstructive Pulmonary Disease) is a chronic condition that affects the lower respiratory system, especially the lungs, but it is not an infection.
C. Tuberculosis (TB) is a bacterial infection that primarily affects the lungs and is considered a lower respiratory infection, not an upper respiratory infection.
D. Acute Coryza is commonly known as the common cold, which is an upper respiratory infection caused by viruses such as rhinoviruses. It affects the nasal passages, throat, and sinuses.

A. The cerebral cortex is involved in higher brain functions like thinking and voluntary control of breathing but does not contain central chemoreceptors.
B. Central chemoreceptors are located in the medulla oblongata, a part of the brain stem. They detect changes in the pH of cerebrospinal fluid, which reflects CO₂ levels in the blood, and help regulate breathing accordingly.
C. The aorta contains peripheral chemoreceptors, not central ones. These aortic bodies monitor blood oxygen, carbon dioxide, and pH, but they are outside the central nervous system.
D. The cerebellum coordinates motor control and balance and does not play a role in chemoreception.