**Core Concept**
Shigellosis is an infectious disease caused by the bacterium Shigella, characterized by diarrhea, abdominal cramps, and fever. The diagnosis of shigellosis is crucial for effective management and prevention of its spread.

**Why the Correct Answer is Right**
The correct answer is stool culture, which involves isolating and identifying the Shigella bacteria from a stool sample. This method is considered the gold standard for diagnosing shigellosis as it allows for the direct detection of the pathogen. Stool culture is particularly useful in the early stages of the disease, when the bacteria are most likely to be present in the stool.

**Why Each Wrong Option is Incorrect**
**Option A:** Blood tests are not specific for diagnosing shigellosis, as they may show non-specific markers of inflammation.

**Option B:** PCR (Polymerase Chain Reaction) is a sensitive method for detecting Shigella DNA in stool samples, but it is not the primary diagnostic method due to its high cost and limited availability.

**Option C:** Endoscopy is not typically used for diagnosing shigellosis, as it is not necessary for the diagnosis of this condition.

**Clinical Pearl / High-Yield Fact**
Shigellosis is a notifiable disease in many countries, and healthcare providers must report suspected cases to public health authorities to prevent outbreaks.

**Correct Answer:** C. Stool culture.