**Core Concept**
Campylobacter is a genus of Gram-negative, thermophilic, and microaerophilic bacteria that are commonly associated with gastrointestinal infections. These bacteria are known to cause symptoms such as diarrhea, abdominal pain, and fever in humans.

**Why the Correct Answer is Right**
Campylobacter jejuni is the most common cause of bacterial gastroenteritis worldwide. The pathogenesis of Campylobacter involves the invasion of intestinal epithelial cells, leading to inflammation and damage to the intestinal mucosa. The bacteria also produce enterotoxins that contribute to the symptoms of gastroenteritis. The immune response to Campylobacter infection can also lead to the development of Guillain-Barré syndrome, a rare but serious autoimmune disorder.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify the most common species of Campylobacter associated with human disease.
**Option B:** This option is incorrect because it does not mention the specific mechanism of pathogenesis of Campylobacter, which involves invasion and toxin production.
**Option C:** This option is incorrect because it does not provide any information about the clinical presentation of Campylobacter infection.

**Clinical Pearl / High-Yield Fact**
Campylobacter infection is often associated with the consumption of undercooked poultry or contaminated water. Proper hand hygiene and cooking practices can help prevent the spread of this infection.

**Correct Answer:** D.