The increasing order of effective nuclear charge (Z_eff) experienced by the electron present in the orbitals is d<p<s.

This is due to the shielding or screening effect t of inner electrons ( nearest to the core, s ) towards the outer shell electrons. S orbital is the nearest to the nucleus so it will experience almost the full positive charge (Ze) of the nucleus; whereas p and d shows decrease in effective nuclear charge because they are more shielded by the inner core electrons, therefore, feel less positive charge attraction by the nucleus and as d orbitals electrons are at more distance than p orbitals the electrons present in it experience less effective nuclear charge .