Which of the following best describes an electric charge?

An electric charge is indeed a fundamental property of matter, just like mass and volume. It refers to the physical property that causes particles to experience a force when placed in an electromagnetic field. Charged particles, such as electrons (which carry a negative charge) and protons (which carry a positive charge), interact with one another through electric forces. This interaction is essential for the structure of atoms, the formation of molecules, and the behavior of materials.

In contrast, the other choices do not accurately define electric charge. For instance, voltage is a measure of electric potential difference, rather than a property or characteristic of matter itself. Electromagnetic radiation is a wave phenomenon consisting of oscillating electric and magnetic fields, not a property of matter. A flowing stream of electrons describes an electric current rather than electric charge itself, as electric charge is a static property that can exist without movement. Therefore, defining electric charge as a fundamental property of matter captures its intrinsic nature in physics.