Talking only about the sensor itself and how it would respond to perfect light patterns right there at the sensor face. Talking about spatial pattern frequencies of less than the limit du jour, e.g. Nyquist et al. Not talking about lenses, apertures, Airy discs, CoC's, etc, etc.
Consider a pattern with black/white line pairs at 2 pixels per pair, perfectly aligned with the pixels of course. Is the resulting contrast 100% e.g. a MTF of 1? Or is it less and, if so, why?