**Core Concept**
The question is testing the student's knowledge of the pharmacological effects of general anaesthetic agents on the autonomic nervous system, specifically their impact on sympathetic stimulation.

**Why the Correct Answer is Right**
Certain general anaesthetic agents can cause sympathetic stimulation, which is characterized by an increase in heart rate, blood pressure, and cardiac output. This effect is primarily mediated through the activation of the sympathetic nervous system, particularly the release of catecholamines such as adrenaline and noradrenaline. One notable general anaesthetic agent that is known to cause sympathetic stimulation is **ketamine**. The mechanism behind this effect involves the blockade of NMDA receptors in the central nervous system, which leads to an increase in the activity of the sympathetic nervous system.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not specified, so we can't evaluate its correctness.
* **Option B:** This option is not specified, so we can't evaluate its correctness.
* **Option C:** This option is not specified, so we can't evaluate its correctness.
* **Option D:** This option is not specified, so we can't evaluate its correctness.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that ketamine can cause sympathetic stimulation, which can be beneficial in certain situations, such as in patients with cardiovascular instability. However, this effect can also be detrimental in patients with pre-existing hypertension or cardiac disease.

**Correct Answer: C. Ketamine.**