Why was the black panther party considered “radical” in the civil rights era?

a) they were endorsed by a wide range of african american leaders of the civil rights movement.
b) the black panthers appealed mainly to more affluent african americans than the older organizations.
c) their policies were widely supported by a wide range of americans throughout the entire united states.
d) their policies of direct confrontation and marxist economic philosophies broke from the established methods of protest.