Final answer:
A point charge has the characteristic of having no volume.
Step-by-step explanation:
A point charge is a mathematical concept used in physics to represent an object with a very small size and concentrated charge at a single point. It is used as a simplification to analyze the behavior of charged objects. In reality, no object can truly have zero size or infinite charge density, but the concept of a point charge is a useful approximation.
A point charge has the characteristic of having no volume (option A). It is a mathematical abstraction and does not occupy any physical space. However, it can still have mass and may or may not have excess protons or electrons (options B and C). Therefore, options B and C are incorrect. A point charge can have mass (option D) because in physics, mass and charge are separate properties. So, the correct characteristic of a point charge is that it has no volume (option A).