Answer:
Alpha radiation
Step-by-step explanation:
We have 3 types of radiation:
- Alpha radiation: it consists of alpha particles (nuclei of helium). This types of radiation is not very penetrating (alpha particles can be easily stopped by a thin sheet of paper), but they are strongly ionising. Therefore, they are not really dangerous if they are outside the body, however if they are already inside the body are extremely dangerous, since they can release a lot of energy in the tissues
- Beta radiation: it consists of fast-moving electrons/positrons. This type of radiation is more penetrating than alpha radiation, but less ionising, since it releases less energy.
- Gamma radiation: it consists of high energy gamma photons. This type of radiation is the most penetrating, since it can easily pass several meters of material (because gamma photons do not interact very often), however it is also the least ionising, for the same reason.
Therefore, the correct answer is
alpha radiation