**Core Concept**
Ketamine is a potent anesthetic agent with analgesic, sedative, and amnestic properties. Its unique pharmacological profile allows for administration via various routes, but some routes are not feasible due to its properties as a controlled substance and potential for abuse.

**Why the Correct Answer is Right**
Ketamine is commonly administered intravenously (IV) for rapid onset and controlled effect. It can also be given intramuscularly (IM) for sedation and analgesia in emergency situations. However, due to its potential for abuse and the difficulty in controlling the dose, oral and rectal routes are not commonly used. The rectal route is particularly problematic as it can lead to rapid absorption and unpredictable effects.

**Why Each Wrong Option is Incorrect**
**Option A:** Intravenous (IV) is a viable route for ketamine administration, providing rapid onset and controlled effect.
**Option B:** Intramuscular (IM) is another acceptable route, commonly used for sedation and analgesia in emergency situations.
**Option C:** This option is not provided, please fill in the correct answer.

**Clinical Pearl / High-Yield Fact**
When administering ketamine, it is essential to consider the patient's weight, age, and medical history to avoid potential side effects, such as increased heart rate and blood pressure.

**Correct Answer: C.