The correct option is D Connect the free end of the electroscope to a point buried under the ground through a conductor.
Charged elecroscope can be neutralised by giving equal amount of opposite charge because same amount of like and unlike charges neutralises the electroscope. Similarly, if we connect it to a conductor connected to deep under ground, we are grounding and neutralising it.
Touching it with a chargeless ebonite rod makes the charges present on the electroscope to flow to the neutral rod. However, at a point of time, charge flow will stop and still some charge will be left in the electroscope.
Transferring an equal amount of same charge would increase the charge on electroscope.