**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) of the genus *Leptotrombidium*. The disease is characterized by fever, headache, and rash, and can progress to more severe symptoms if left untreated.

**Why the Correct Answer is Right**
The correct answer is incorrect because the adult female trombiculid mite does not feed on vertebrate hosts. Instead, the larval stage of the mite, known as the chigger, is the vector that transmits *Orientia tsutsugamushi* to humans. The chigger attaches to the skin and injects saliva that contains the bacteria, leading to infection. Adult mites, on the other hand, feed on plant sap and do not come into contact with vertebrate hosts.

**Why Each Wrong Option is Incorrect**
**Option A:** The causative organism of scrub typhus is indeed *Orientia tsutsugamushi*, not *O. Tsutsugamoshi*. The correct species name is *Orientia tsutsugamushi*.
**Option B:** The vector of scrub typhus is indeed the trombiculid mite, specifically the larval stage known as the chigger. This option is correct, but it is not the answer to the question.
**Option D:** Tetracycline is indeed the drug of choice for treating scrub typhus. It is effective against *Orientia tsutsugamushi* and can be used to treat the disease in its early stages.

**Clinical Pearl / High-Yield Fact**
It's essential to note that scrub typhus is a preventable disease through the use of protective clothing and insecticides, as well as early recognition and treatment of infected patients. Prompt treatment with tetracycline or doxycycline can significantly reduce the risk of complications and mortality.

**✓ Correct Answer: C. Adult female feeds on vertebrate hosts**