## Core Concept
The use of radioactive iodine (I-131) in the treatment of thyroid carcinoma is based on the principle that thyroid cells, including cancerous ones, take up iodine. This allows for targeted destruction of thyroid tissue and cancer cells. The dose of I-131 depends on several factors, including the type and extent of the disease.

## Why the Correct Answer is Right
The correct dose of I-131 for patients with carcinoma of the thyroid can vary, but a common dose for ablation of the thyroid remnant or for treatment of certain types of thyroid cancer is around 30 to 100 mCi (millicuries). However, for **ablation** or **treatment of thyroid cancer**, a dose of **30 mCi** or **100 mCi** might be considered standard in many protocols, depending on the specific circumstances. The specified correct answer, **100 mCi**, falls within therapeutic ranges used for managing thyroid cancer, especially for ablation of remnants or for therapy in certain stages or types of thyroid cancer.

## Why Each Wrong Option is Incorrect
- **Option A:** 10 mCi is lower than typically used for therapeutic purposes in thyroid cancer treatment, although it might be used for diagnostic purposes.
- **Option B:** 50 mCi could be considered a dose for some therapeutic interventions but might not be as commonly referenced as 100 mCi for specific indications like ablation or therapy in thyroid cancer.
- **Option D:** 200 mCi seems excessively high for a standard dose in the treatment of thyroid carcinoma and could increase the risk of side effects without providing additional therapeutic benefit.

## Clinical Pearl / High-Yield Fact
A key point to remember is that I-131 therapy is tailored to the individual, based on factors like the type of thyroid cancer, the extent of disease, and the patient's overall health. Dosage can significantly impact outcomes, making it crucial to follow established guidelines and protocols.

## Correct Answer Line
**Correct Answer: C. 100 mCi.**