It is c I hope I helped out with this question!.
the fire spreading is what represents the form of heat transferring from one atom to another within an object and direct contact
The difference is due to the degree of dissociation of the substances. HCl dissociates completely into ions when added to water, while this is not the case for HC₂H₃O₂; therefore, HCl has a lower pH.
The answer is Electrons move between objects. The reason this is known is that the acts of friction and conduction (from the little picture he could not put in) involves contact to be known as friction and conduction. Without contact the electrons could not move between objects. I also got this question right on the test. That's how I know this is right. I hope this helps. ( ͡° ͜ʖ ͡°)