Answer:
The particle with the greatest mass is:
The alpha particle.
Step-by-step explanation:
The mass of the Alpha Particle is considered to be 4 amu, which is the biggest of all these options.
The mass o the beta particle is considered to be 1/2000 amu which is considered to be the third place of the elements shown.
The neutron has a mass of 1 amu which makes it larger than the beta particle's mass and brings it to the second place of our rank.
The gamma particle mass is considered to be 0 because it is made of pure energy. Therefore it occupies the fourth place in our rank.