Hello!
There are three main types of radiation decay. These are called alpha, beta, and gamma decays.
Alpha particles are helium atoms with a +2 charge. They have no electrons, two protons, and two neutrons. It's symbol is 4/2He or 4/2α.
Beta particles are like an electron with a -1 charge. It has zero protons and neutrons. These particles have two symbols: 0/-1e or 0/-1β.
Gamma particles are photons, which are made of light energy. It has no mass and has a symbol as 0/0γ or three squiggly lines.
Looking at the given nuclear reaction, it has 0/-1e in it's equation.
Therefore, the radiation emitted in the nuclear equation is beta, the second choice.