  The longitudinal and transverse nuclear responses to inclusive electron
scattering reactions are analyzed within the Random Phase Approximation (RPA)
framework. Several residual interactions are considered and it is shown that
the exchange terms in the RPA make very difficult to find an effective residual
interaction capable of reproducing simultaneously the quasielastic peak of both
the longitudinal and transverse responses. By means of a simplified model it is
illustrated that the residual interaction used in a ring approximation must
fulfill some restrictions in order to qualitatively reproduce the full RPA
results.
