**Core Concept**
Topoisomerase I inhibitors are a class of chemotherapeutic agents that target the enzyme topoisomerase I, which is involved in DNA replication and transcription. By inhibiting topoisomerase I, these drugs induce DNA damage and apoptosis in rapidly dividing cancer cells.

**Why the Correct Answer is Right**
Irinotecan (CPT-11) is a topoisomerase I inhibitor that works by stabilizing the cleavage complex of topoisomerase I, preventing the enzyme from religating the DNA strand and leading to DNA damage and cell death. This mechanism is particularly effective in cancer cells that are rapidly dividing and rely on topoisomerase I for DNA replication.

**Why Each Wrong Option is Incorrect**
* **Option A:** Topotecan is a topoisomerase I inhibitor as well, but it is not the correct answer in this context.
* **Option B:** Cisplatin is a platinum-based chemotherapeutic agent that works by crosslinking DNA, but it is not a topoisomerase I inhibitor.
* **Option D:** Docetaxel is a taxane that works by stabilizing microtubules, preventing cell division, but it is not a topoisomerase I inhibitor.

**Clinical Pearl / High-Yield Fact**
Topoisomerase I inhibitors, such as irinotecan, are associated with a higher risk of diarrhea and neutropenia compared to other chemotherapeutic agents. Patients receiving these drugs should be closely monitored for these adverse effects.

**Correct Answer:** C. Irinotecan.