**Core Concept**
Radiation-induced cancer occurs when ionizing radiation damages the DNA of cells, leading to genetic mutations and uncontrolled cell growth. This phenomenon is a well-documented consequence of exposure to radiation from various sources, including medical treatments, nuclear accidents, and environmental radiation.

**Why the Correct Answer is Right**
Leukemia, particularly acute myeloid leukemia (AML), is a classic example of radiation-induced cancer. Ionizing radiation can cause chromosomal breaks and aberrations, leading to mutations in genes involved in cell cycle regulation, DNA repair, and apoptosis. The most susceptible cells are those in the bone marrow, where hematopoietic stem cells are located. Radiation exposure can trigger the development of leukemia by inducing genetic changes in these stem cells.

**Why Each Wrong Option is Incorrect**
**Option A:** Thyroid cancer is a possible consequence of radiation exposure, but it is not the most common example of radiation-induced cancer.
**Option B:** Lymphoma is another type of cancer that can be associated with radiation exposure, but it is not as strongly linked to radiation as leukemia.
**Option C:** Brain tumors can be caused by radiation exposure, but they are not as directly linked to radiation as leukemia.

**Clinical Pearl / High-Yield Fact**
The risk of radiation-induced cancer increases with the dose and duration of radiation exposure. Medical professionals and patients should be aware of the potential risks and take steps to minimize exposure whenever possible.

**Correct Answer: C. Leukemia**