Radioactive substances emit alpha particle, beta particles and gamma radiation for getting satiability.
When alpha particles are emitted from the radioactive substance, then it is called as alpha decay.
When high energy electromagnetic radiation is emitted then it is called as x rays emission.
A product of the decomposition of a proton doesnot contains an electron.
Hence, the option A, C, and D are wrong.
Beta particle contains electrons and positron. Hence, the emission of the beta radiation emits electrons.
Hence, the correct option is.