Show that a simple group of order 168 must be isomorphic to a subgroup of the alternating group A₈. a) Every simple group of order 168 is isomorphic to A₈. b) A simple group of order 168 cannot be isomorphic to A₈. c) A simple group of order 168 must be a subgroup of A₈. d) There exists a simple group of order 168 not isomorphic to any subgroup of A₈.