The right answer is 4He2+
Alpha particle looks like the nucleus of helium, but without electrons.
Alpha particles or alpha rays are a form of radiation emitted by unstable nuclei of great atomic mass. They consist of two protons and two neutrons combined into a particle identical to the helium nucleus 4 (helium); they can therefore be written 4He2 +.
The mass of an alpha particle is 6.644657 × 10-27 kg, which equates to a mass energy of 3.72738 GeV.