Which one of the following can charge an insulator?

Insulators are materials that do not allow electrons to flow freely, making them poor conductors of current electricity. However, insulators can be charged through the process of static electricity, often via the triboelectric effect or friction. When two different materials, particularly insulators like plastic and wool, are rubbed together, electrons are transferred from one to the other [2]. This results in one object becoming positively charged and the other negatively charged [2]. These charges are termed 'static' because they remain stationary on the surface of the insulator rather than flowing through it [1]. While current electricity involves the continuous flow of electrons through conductors, static electricity deals with the buildup of non-moving charges on surfaces. Magnetic and gravitational fields do not inherently transfer net electric charge to a neutral insulator [1].

Sources

1. [2] Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 5: Exploring Forces > Activity 5.6: Let us experiment > p. 70
2. [1] https://www.britannica.com/science/static-electricity