Which one of the following is true?

The assertion regarding a linear relationship between exposure to ionizing radiation and gene mutation is grounded in established scientific understanding. Research indicates that even low levels of ionizing radiation can lead to genetic damage, including mutations. This relationship is often described by the linear no-threshold model, which posits that the risk of genetic effects continues to increase proportionately with the dose of radiation, without a safe threshold level below which risk is zero.

This is significant as it underscores the necessity for stringent safety measures and monitoring for populations exposed to ionizing radiation, such as medical personnel involved in radiotherapy. Understanding this relationship is crucial for risk assessment and implementing protective measures to minimize the chances of adverse genetic effects over time.

The other statements lack scientific support: it is known that low levels of exposure can indeed pose risks, chromosomal damage is a recognized consequence of exposure to radioactive isotopes, and studies do indicate increased mutation frequency among radiotherapy staff, highlighting the importance of protective protocols in such environments.