## **Core Concept**
C-reactive protein (CRP) is an acute-phase protein that increases in response to inflammation. It is named for its ability to react with the C polysaccharide of pneumococcus. CRP is produced in the liver in response to factors released by fat cells (macrophages) and plays a key role in the body's inflammatory response.

## **Why the Correct Answer is Right**
The statement that CRP is **raised in acute pneumococcal infection** is correct. CRP levels rise significantly within hours of the onset of inflammation or infection, making it a sensitive marker for acute inflammatory conditions, including acute pneumococcal infections. CRP is not an antibody but a protein that binds to phospholipids, specifically the C-polysaccharide of Streptococcus pneumoniae, and other substances released by necrotic cells. It activates the complement system and enhances phagocytosis.

## **Why Each Wrong Option is Incorrect**
- **Option A:** Detected by precipitation with carbohydrate - This is partially correct in principle since CRP was originally identified by its reaction with C polysaccharide of pneumococcus. However, it is more accurately detected by latex agglutination or ELISA.
- **Option C:** It is an antibody - This is incorrect. CRP is not an immunoglobulin; it is an acute-phase protein that does not have antigen-specific binding like antibodies do.
- **Option D:** Detected by agglutination test - While it's true that CRP can be detected by agglutination tests (like latex agglutination), saying this option is incorrect is misleading. However, the specificity and sensitivity of detection methods have evolved.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that CRP is a **non-specific marker of inflammation**. High sensitivity CRP (hs-CRP) is used to assess cardiovascular risk, with levels 3 mg/L indicating high risk.

## **Correct Answer:** B.