Which type of tissue is most sensitive to radiation exposure?

Lymphoid tissue is the most sensitive to radiation exposure due to its high rate of cell proliferation and its critical role in the immune system. Tissues that are rapidly dividing tend to be more susceptible to radiation damage because radiation primarily affects cellular DNA during division. Lymphoid tissue, which includes cells such as lymphocytes, is actively involved in generating the body's immune response and has a relatively high turnover rate compared to other tissues.

While nervous tissue can be sensitive to radiation due to the potential for long-term effects, it does not have the same proliferation rates as lymphoid tissue. Muscle tissue is generally more resistant to radiation because it has lower cell turnover rates and is more differentiated. Epithelial tissue, while sensitive, typically has a varying degree of sensitivity depending on its type and role in the body, and is generally not as sensitive as lymphoid tissue. Thus, lymphoid tissue stands out as the most affected by radiation exposure, making it the correct answer.