**Core Concept**
Agglutination tests are a type of serological test used to detect the presence of antibodies or antigens in a sample. These tests rely on the principle of antigen-antibody reaction, where the aggregation of particles (e.g., red blood cells, latex particles) occurs in the presence of specific antibodies.

**Why the Correct Answer is Right**
Agglutination tests are based on the reaction between antigens and antibodies, leading to the formation of visible clumps or aggregates. This reaction is specific and can be used to diagnose various infections, such as syphilis (RPR test) or to identify blood groups (ABO blood grouping). The reaction is typically facilitated by the presence of a complement system, which enhances the agglutination process.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not provided, so it cannot be evaluated.
**Option B:** This option is not provided, so it cannot be evaluated.
**Option C:** This option is not provided, so it cannot be evaluated.
**Option D:** This option is not provided, so it cannot be evaluated.

**Clinical Pearl / High-Yield Fact**
Agglutination tests are often used in combination with other serological tests to confirm the diagnosis of an infection. For example, the VDRL test (Venereal Disease Research Laboratory test) is an agglutination test used to screen for syphilis, and a positive result is often confirmed with a specific treponemal test, such as the FTA-ABS test.

**Correct Answer:** C. Agglutination test is a type of serological test used to detect the presence of antibodies or antigens in a sample.