You know from the definition provided of progressive taxation that those who “feel it unjust” that the “most industrious” are “penalized” would definitely be against progressive taxation, so rail against matches in the first blank.

The word unjust is a good clue that moralists matches in the second blank (the other two words make no sense — autodidacts are people who teach themselves and recidivists are people who return to committing crimes). In the third blank, you need another group of people who are against progressive taxation but who are different from the moralists — in this case, because they are making a practical argument, not a
moral one. Only utilitarians matches.

thanks