**Core Concept**
Nigro's regimen refers to a specific chemoradiation protocol used in the treatment of anal cancer. This regimen involves a combination of radiation therapy and chemotherapy to achieve local control of the tumor.

**Why the Correct Answer is Right**
Nigro's regimen typically consists of a combination of 28-30 Gy of radiation therapy and concurrent chemotherapy with 5-fluorouracil (5-FU) and mitomycin-C (MMC). The radiation is delivered to the tumor site, while the chemotherapy agents are administered systemically to target any micrometastatic disease. The concurrent administration of radiation and chemotherapy is crucial in Nigro's regimen, as it enhances the radiosensitizing effects of the chemotherapy agents, leading to improved local control rates.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because Nigro's regimen does not typically involve the use of cisplatin as a chemotherapy agent. While cisplatin is a commonly used chemotherapeutic agent in the treatment of various cancers, it is not a standard component of Nigro's regimen.
* **Option B:** This option is incorrect because Nigro's regimen involves a combination of radiation therapy and chemotherapy, not radiation therapy alone. The concurrent administration of chemotherapy agents is a critical component of this regimen.
* **Option D:** This option is incorrect because Nigro's regimen does not typically involve a total dose of radiation therapy exceeding 30 Gy. The standard dose of radiation therapy used in Nigro's regimen is 28-30 Gy.

**Clinical Pearl / High-Yield Fact**
Nigro's regimen is a classic example of a chemoradiation protocol used in the treatment of anal cancer, and its success has led to the development of similar regimens for other cancers, such as cervical and esophageal cancer.

**Correct Answer: C. 5-fluorouracil (5-FU) and mitomycin-C (MMC) are used concurrently with radiation therapy in Nigro's regimen.**