* β particle: A beta particle is essentially a high-energy electron, which has a negative charge.
* γ rays: Gamma rays are electromagnetic radiation, and they have no charge.
* Protons: Protons are found in the nucleus of an atom and have a positive charge.
* α particle: Alpha particles are essentially helium nuclei, consisting of two protons and two neutrons. They have a positive charge (due to the two protons).
Therefore, the correct answer is 1. β particle.
