Which of the following is caused by radiation exposure to the human body?

Ionization is a fundamental process that occurs when radiation interacts with matter, including the human body. When radiation, particularly ionizing radiation such as X-rays or gamma rays, passes through tissues, it can impart enough energy to remove tightly bound electrons from atoms, resulting in the formation of ions. This ionization can lead to a range of biological effects, including damage to cellular structures and genetic material.

The consequences of ionization can manifest in various ways, such as disrupting molecular bonds, leading to structural changes in DNA, proteins, and other essential molecules within cells. These changes can initiate cellular damage that might result in mutations, cell death, or cancer, depending on the extent of the exposure and the body's ability to repair the damage.

In contrast, the other options do not represent direct effects caused by radiation exposure. Direct DNA repair refers to the biological mechanisms that cells utilize to fix damaged DNA, which may be activated following radiation exposure but is not a result of radiation itself. Chemical alteration of proteins can occur as a consequence of ionization but is not the primary process associated specifically with radiation exposure. Similarly, cellular regeneration refers to the natural processes of cell recovery and replacement, which are continuously happening in the body and are not directly caused by radiation exposure. Thus