Answer: The correct answer is alpha radiation.
For the given options:
Option 1: Alpha
Alpha decay is defined as the process in which alpha particle is emitted. In this process, a heavier nuclei decays into a lighter nuclei. The alpha particle released carries a charge of +2 units. The released alpha particle is also known as helium nucleus.
Option 2: Beta
Beta decay is defined as the process in which beta particle is emitted. In this process, a neutron gets converted to a proton and an electron. The released beta particle is also known as electron.
Option 3: Gamma
Gamma decay is defined as the process in which an unstable nuclei gives off excess energy by a spontaneous electromagnetic process and thus releases . These radiations does not carry any charge and are electrically neutral.
Option 4: Isotope
Isotope is defined as the chemical specie which belong to the same element but differ in their molecular mass.
Hence, the correct answer is alpha radiation.