What happens to living cells when they undergo ionisation from radiation?

When living cells undergo ionisation from radiation, the energy from the radiation can strip electrons from atoms within the cells, leading to damage at the molecular and cellular levels. This damage can affect DNA, and if the genetic material is altered in a way that disrupts normal cellular regulation, it can lead to uncontrolled cell growth. This uncontrolled growth is a hallmark of cancer. Therefore, cells that experience significant ionisation can potentially become cancerous, making this the correct choice.

The other options describe outcomes that are not accurate in the context of ionisation. For example, replication rates do not initially become faster due to ionisation; rather, severe damage could impede replication or lead to cell death instead. Cells do not enhance their energy levels as a result of ionising radiation; rather, the process typically results in damage and loss of functional integrity. Finally, cells do not become immune to future radiation exposure; previous exposure might actually increase susceptibility to genetic damage from subsequent radiation, rather than conferring any form of immunity. Thus, the correct understanding is that ionisation from radiation can lead to cancerous changes in living cells.