**Core Concept**
Leprosy, caused by the bacterium *Mycobacterium leprae*, is a chronic infection that affects the skin and peripheral nerves. There are different types of leprosy, classified based on the immune response to the bacteria.

**Why the Correct Answer is Right**
The tuberculoid form of leprosy is characterized by a strong cell-mediated immune response, resulting in a limited number of lesions, typically one or few. This is due to the presence of a high number of CD4+ T cells and the production of cytokines such as interferon-gamma, which help to contain the infection. In contrast, the lepromatous form of leprosy is associated with a weaker immune response, leading to widespread dissemination of the bacteria and multiple lesions.

**Why Each Wrong Option is Incorrect**
**Option A:** The lepromatous form of leprosy is characterized by multiple lesions, not a single lesion.
**Option B:** The borderline form of leprosy is a transitional form between the tuberculoid and lepromatous forms, and can present with multiple lesions.
**Option C:** The dimorphic form of leprosy is not a recognized classification of leprosy.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the type of leprosy is determined by the immune response, with tuberculoid leprosy being characterized by a strong cell-mediated immune response and lepromatous leprosy being characterized by a weaker immune response.

**Correct Answer:** C.