Answer: The correct answer is option 2.
Step-by-step explanation:
There are 4 types of decay process, in which a radioisotope can become stable. They are:
1.) Alpha decay: In this process, alpha particles are emitted when a heavier nuclei decays into lighter nuclei. The alpha particle released has a charge of +2 units and has a mass of 4 units. The alpha particle released is also known as helium atom.
2.) Beta-decay: In this process, a neutron is converted into a proton and an electron with the release of a beta-particle. The beta particle released carries a charge of -1 units. and it does not have any mass.
3.) Gamma ray emission: In this process, an unstable nuclei releases excess energy by a spontaneous electromagnetic process and
are emitted. These radiations does not carry any charge and are electrically neutral.
4.) Positron decay: In this process, a proton is converted to a neutron and an electron neutrino and positron particles are released. This particle carries a charge of +1 units and does not have any mass. This type of decay is also known as beta-plus decay.

From the above information, gamma decay is represented as
Hence, the correct answer is Option 2.