Final answer:
Electric charge is quantized, meaning it comes in discrete amounts, with the smallest amount being an integer multiple of the charge of one proton.
Step-by-step explanation:
Electric charge is quantized, which means it comes in discrete amounts and there is a smallest possible amount of charge. In the SI system, the smallest amount of charge is e = 1.602 × 10-19 C. No free particle can have less charge than this, so the charge on any object must be an integer multiple of this amount. For example, all macroscopic charged objects have charge because electrons have either been added or taken away from them, resulting in a net charge. Therefore, the correct answer is c. is an integer multiple of the charge of one proton.