Which of the following exhibit the highest level of radiosensitivity?

Unborn children exhibit the highest level of radiosensitivity due to several factors related to their rapid cell division and development. During gestation, particularly in the first trimester, the cells are undergoing significant proliferation and differentiation. This phase is critical for the normal development of tissues and organs, making these cells more susceptible to the damaging effects of ionizing radiation.

When radiation exposure occurs, it can result in higher rates of cell death or mutations in rapidly dividing cells, which can lead to developmental abnormalities or increase the risk of cancer later in life. Additionally, the protective mechanisms, such as DNA repair systems, are still developing in unborn children, further increasing their vulnerability.

Newborns, while also sensitive to radiation, do not reach the same level of radiosensitivity as unborn children because their cells have partially differentiated and their growth has stabilized compared to the embryonic stage. Adults, on the other hand, have more mature cells and established repair mechanisms, making them less sensitive to radiation. Teenagers, while still growing and developing, are not as radiosensitive as unborn children due to the level of maturation and differentiation that has occurred.