**Core Concept**
Purple toe syndrome, also known as purple glove syndrome, is a rare but potentially serious condition characterized by purple discoloration of the toes or hands. It occurs due to the extravasation of a chemotherapeutic agent, typically vinca alkaloids like vincristine, into the soft tissues.

**Why the Correct Answer is Right**
The extravasation of vinca alkaloids leads to the inhibition of microtubule assembly, causing axonal degeneration and subsequent ischemia. This results in the characteristic purple discoloration due to the release of histamine and the breakdown of blood vessels. The condition is often associated with the use of intravenous vinca alkaloids in cancer treatment.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as it is not directly associated with purple toe syndrome. While it may have other side effects, it is not the primary cause of this condition.
**Option B:** This option is incorrect as it is not typically associated with extravasation and purple discoloration. Its side effects may include nausea and vomiting, but it is not the primary cause of purple toe syndrome.
**Option C:** This option is incorrect as it is not directly associated with purple toe syndrome. While it may have other side effects, it is not the primary cause of this condition.

**Clinical Pearl / High-Yield Fact**
When administering vinca alkaloids, it is essential to ensure proper intravenous access and to monitor the patient for signs of extravasation. If extravasation is suspected, the affected limb should be elevated, and the infusion should be discontinued immediately.

**Correct Answer:** C. Vincristine.