Which of the following represents an alpha particle?

An alpha particle is a specific type of nuclear particle that consists of two protons and two neutrons, making it identical to the nucleus of a helium-4 atom. In nuclear notation, this is represented as 4/2He, indicating it has a mass number of 4 (the total number of protons and neutrons) and an atomic number of 2 (the number of protons). The designation (2+) refers to its positive charge, as it consists of two positively charged protons, while the two neutrons do not contribute to the charge. This is why the choice representing an alpha particle is correct, as it accurately reflects the structure and characteristics of an alpha particle.

Other options represent different particles: for example, one option represents a neutron, another represents beryllium-8, and a different one represents a hydrogen isotope known as deuterium, which all do not match the composition of an alpha particle.