a. The leaves get closer together.
Work Step by Step
The electroscope starts out neutral. When the positively charged glass rod comes in contact with the electroscope, the excess amount of positive charge on the glass rod spreads out onto the electroscope leaving the electroscope with an excess positive charge. Thus, the leaves in the electroscope spread apart because they have an uneven distribution of charge of excess positive charge. We know this and this is what the question tells us. Now, when the negatively charged plastic rod comes close to but in contact with the electroscope, the electroscope is polarized so that the surface area nearest to the negatively charged plastic rod builds up an excess positive charge on the surface near the plastic rod. This brings some of the excess positive charge that the glass rod left on the electroscope to that are so the leaves of the electroscope loses some of that excess positive charge. Because it loses some of the excess positive charge, the gold leaves move closer together since there is a more even distribution of charge. Option a. is correct.