I believe the correct answer from the choices listed above is option A. The topic that the teacher is talking about would be distillation of a mixture. Gasoline is processed by distillation. Hope this answers the question. Have a nice day.
Hope this helps!
https://youtu.be/MT5tKijKZwQ
wherears one hydrogen atom has a mass of approximately 1 u ,1 mol of h atoms has a mass of approximately 1 gram and wherears one sodium atom has an approximately 1 gram and one sodium atom have approximate mass of 23 u