Correct answer only !

when an uncharged student (standing on an insulating mat) touches a negatively charged van de graaff generator, this is an example of charging by

Conduction

Explanation:

When two conducting bodies are connected to each other by conducting wire then the charge of one body is transferred to other body. This phenomenon of charge transfer is known as Conduction Process.

Here it is given that an uncharged student standing on insulating mat touches a negatively charged Van de Graaff generator then since we know that human body is a conductor so when we touch the generator charge will flow to our body by conducting medium

So here this phenomenon is charging by Conduction Method

So correct answer would be

CONDUCTION