Which substance below is resonance stabilized by delocalized pi electrons?

a. Benzene

b. Hydrochloric acid

c. Hydrogen gas

d. Methane

e. Potassium bromide

If you do not this, I suggest brushing up on delocalization as well as sigma/pi bonds. Benzene is the only one of the 5 with any pi bonds, so this should be a relatively easy question if you are familiar with the concepts. I would search up a detailed (not to detailed though) explanation of both.