**Core Concept**
The Kahn test is a serological test used to detect the presence of syphilis in patients. It involves the reaction between cardiolipin, an antigen derived from beef heart, and the antibodies produced in response to the syphilis infection.

**Why the Correct Answer is Right**
The Kahn test is a type of non-treponemal test, which detects the antibodies that are not specific to the syphilis spirochete but are present in response to the infection. These antibodies bind to cardiolipin, an antigen present in the test reagent, causing a visible precipitate to form. The test is widely used due to its simplicity and sensitivity, but it has limitations, such as false-positive results in patients with other conditions like yaws or Lyme disease.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because the Kahn test is not a treponemal test, which detects antibodies specifically against the syphilis spirochete. Treponemal tests are more specific but can remain positive for life even after treatment.
* **Option B:** This option is incorrect because the Kahn test is not a rapid plasma reagin (RPR) test, which is another type of non-treponemal test used to diagnose syphilis. While both tests detect similar antibodies, they differ in their sensitivity and specificity.
* **Option C:** This option is incorrect because the Kahn test is not a fluorescent treponemal antibody absorption (FTA-ABS) test, which is a treponemal test used to confirm the diagnosis of syphilis.

**Clinical Pearl / High-Yield Fact**
It's essential to note that non-treponemal tests like the Kahn test can produce false-positive results due to various factors, including recent blood transfusions or infections. Therefore, a confirmatory treponemal test is often recommended to ensure accurate diagnosis.

**Correct Answer: C. Kahn test is a type of non-treponemal test used to detect antibodies against syphilis.**