**Core Concept**
Boil, also known as furuncle, is a skin infection caused by Staphylococcus aureus. It occurs when the hair follicle becomes infected, leading to localized inflammation and pus formation. This condition is a result of the bacterial infection causing damage to the surrounding skin tissue.

**Why the Correct Answer is Right**
The correct answer is **B**. Boil cannot occur at the site of the scalp, as the scalp has a unique structure with tightly adherent hair follicles that are covered by a thick layer of keratin, making it difficult for the bacteria to penetrate and cause infection. Additionally, the scalp's rich blood supply and high oxygen tension also contribute to the reduced likelihood of boil formation.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because boils can indeed occur on the face, including the nose, cheeks, and chin. The hair follicles on these areas are susceptible to infection.
**Option C:** This option is incorrect because boils can occur on the back, neck, and other parts of the body where there is a high concentration of hair follicles.

**Clinical Pearl / High-Yield Fact**
Boils are often caused by Staphylococcus aureus, which can also cause more severe infections, such as cellulitis, abscesses, and sepsis. It's essential to treat boils promptly and effectively to prevent the spread of infection.

**Correct Answer: C. Boil cannot occur at the site of the scalp.**