Correct answer: CH2=CH2, CH3-NH2, CH3-CH2-OH, benzene
Set 2 contains H3O(+), a cation/electrophile, so it is not an all-nucleophile set. Set 1 includes:CH2 (carbene), which is electrophilic. Set 4 includes CS2 and toluene which are weak, and the inclusion of typical electrophilic considerations rules them out. Set 3 (ethene with pi electrons, methylamine with N lone pair, ethanol with O lone pair, benzene with aromatic pi cloud) are all electron-rich nucleophiles.