When the negatively charged rod touches the insulating foam cup, the electrons from the rod will not transfer to the cup, since the cup is an insulator and does not allow free movement of charge. Instead, the negatively charged rod will induce a separation of charges in the foam cup. Because the rod is negatively charged, it will repel electrons within the foam cup away from the point of contact. This movement of electrons will create a localized area of positive charge where the rod made contact, as there will be a deficit of electrons there.
Therefore, the correct outcome from the provided options is:
The electrons will transfer to the cup and will remain in a concentrated, positively charged area on the cup where the rod was placed.
This effectively results in the foam cup becoming positively charged due to the deficit of electrons at the point of contact. However, since the foam is an insulator, there won't be a transfer of charge to the metal can, and the can itself will remain neutral unless influenced by other means.