Answer: A)They generate electricity by contact
Explanation: triboelectricity can be simply defined as a phenomenon where static electricity is produced when two different materials are vigorously and continuously rubbed or come in contact with each other. This vigorous and continous contact allow electrons to jump from one material (atom) to another there by creating static electricity.
This characteristics is evident when an individual walks across a carpet while wearing a wool socks, as the wool and the carpet vigorously and continuously rub against one another, electrons are transfered from the carpet to the socks which spread all over the surface of the body. (The body becomes negativity charged while the carpet becomes positively charged) This is why the individual will feel a shock sensation when he or she goes on to touch the door knob due to the static electricity generated.