**Core Concept**
Campylobacter jejuni is a gram-negative, thermophilic bacterium that causes diarrhea, often accompanied by abdominal cramps. The bacterium is commonly isolated from stool specimens, but it requires specific cultural conditions to grow.

**Why the Correct Answer is Right**
The method of choice for culturing Campylobacter jejuni involves using a selective medium, such as Skirrow's medium, which contains antibiotics to inhibit the growth of other bacteria. The culture is incubated at 42°C under microaerophilic conditions, which is essential for the growth of Campylobacter species. The use of a temperature gradient incubator helps to create the optimal temperature conditions for the growth of Campylobacter jejuni.

**Why Each Wrong Option is Incorrect**
* **Option A:** MacConkey agar is a selective medium for gram-negative bacteria, but it is not the method of choice for culturing Campylobacter jejuni.
* **Option B:** Blood agar is a general-purpose medium, but it does not provide the selective conditions required for the growth of Campylobacter jejuni.
* **Option D:** Cary-Blair medium is used for the transport of stool specimens, but it is not a selective medium for culturing Campylobacter jejuni.

**Clinical Pearl / High-Yield Fact**
Campylobacter jejuni is a leading cause of bacterial gastroenteritis, and it can be transmitted through contaminated food and water, as well as through direct contact with infected animals. The bacterium is often isolated from poultry and other animals, which can serve as a source of infection for humans.

**Correct Answer: C. Skirrow's medium.**