The answer is D: pilgrims from all three states.
The faults and shortcomings of the pilgrims are described with different levels of mockery, It didn't matter if they were from nobility (Knight, Wife of Bath), church (Pardoner, Nuns' Priest, Summoner, Prioress) or peansentry (Miller, Reeve), all thre estates. He even apologizes for being too harsh or rude.