Which of the following particles is emitted during alpha decay?

During alpha decay, the nucleus of an atom releases an alpha particle, which is composed of two protons and two neutrons. This process leads to a decrease in the atomic number by two and the mass number by four, effectively transforming the original atom into a different element.

The correct choice, alpha particles, specifically represent this emitted particle during the decay process. The transformation resulting from this emission is a crucial aspect of understanding radioactive decay and nuclear reactions, illustrating how elements change when they undergo such processes.

It's important to differentiate alpha particles from the other choices provided. Electrons are associated with beta decay, where a neutron is transformed into a proton with the emission of an electron. Neutrons are not emitted during alpha decay; instead, they are part of the alpha particle itself. Beta particles, which are high-energy, high-speed electrons or positrons emitted during beta decay, also do not occur in alpha decay. Thus, recognizing that alpha particles are specifically tied to the process of alpha decay clarifies why this option is the correct answer.