Two helium-3 nuclei fuse together to form a helium-4 nucleus and two of particle XXX. The equation for this process is:
23He+23He→24He+2X^{3}_{2}\text{He} + ^{3}_{2}\text{He} \rightarrow ^{4}_{2}\text{He} + 2\text{X}23He+23He→24He+2X
What is XXX?
electron
neutron
positron
proton