d
\((d)\) Polar Aprotic Solvents : Aprotic solvents are those solvents whose molecules do not have a hydrogen atom that is attached to an atom .of an electronegative element.  A number of polar aprotic solvents have come into wide use by chemists because they are especially useful in \(S_{N^2}\) reactions. Several examples are the following

All of these solvents \((DMF, DMSO, DMA,\) and \(HMPA)\) dissolve ionic compounds,  and they solvate cations very well. They do so in the same way that pro tic solvents  solvate cations : by orienting their negative ends around the cation and by donating  unshared electron pairs to vacant orbitals of the cation