Which of the following are properties of mechanical waves? A. Waves transport energy, but not matter.
B. Energy travels toward the source in all wave motion.
C. The particles of the medium always move parallel to the wave
motion.
D. The three categories of mechanical waves are transverse,
longitudinal, and surface waves.

when insulating materials rub against each other, they may become electrically charged . electrons , which are negatively charged, may be 'rubbed off' one material and on to the other. the material that gains electrons becomes negatively charged. the material that loses electrons is left with a positive charge.

does anyone know or what?

i really dont know but i will try okay.

so i think u would just add all them up and get your answer..