Which of the following is NOT a method of producing electric charge?

The choice identifying convection as not a method of producing electric charge is correct because convection primarily refers to the transfer of heat through the movement of fluids (gases or liquids) and does not involve the generation of electric charge.

In contrast, friction generates electric charge through the contact between two different materials, allowing electrons to be transferred from one surface to another. Conduction involves the transfer of charge through direct contact between materials, allowing electrons to flow from a conductor with excess charge to one with a deficiency. Induction is a method where a charged object can induce an electric charge in a nearby object without direct contact, utilizing the electric field around the charged object to influence the distribution of charges in another object.

Since convection does not involve any of these processes related to charge generation, it is correctly identified as the method that does not produce electric charge.