**Core Concept**
Scrub typhus is a zoonotic disease caused by the bacterium Orientia tsutsugamushi, transmitted to humans through the bite of infected chiggers (larval mites). This disease is prevalent in rural areas of Asia and the Pacific Islands.

**Why the Correct Answer is Right**
The correct vector for scrub typhus is the chigger, specifically the larval stage of the trombiculid mite. Chiggers are ectoparasites that feed on the blood of vertebrates, and they become infected with Orientia tsutsugamushi when they feed on infected rodents. When an infected chigger bites a human, it transmits the bacteria, causing scrub typhus.

**Why Each Wrong Option is Incorrect**
**Option A:** The tick is a vector for other diseases such as Lyme disease, Rocky Mountain spotted fever, and anaplasmosis, but not scrub typhus.
**Option B:** The flea is a vector for diseases such as bubonic plague, but not scrub typhus.
**Option C:** The mosquito is a vector for diseases such as malaria, dengue fever, and Zika virus, but not scrub typhus.

**Clinical Pearl / High-Yield Fact**
Chiggers are tiny, six-legged mites that are barely visible to the naked eye. When a chigger bites, it injects saliva that causes intense itching and inflammation, leading to characteristic skin lesions.

**Correct Answer: C. Mosquito.