25. Wilkinson's catalyst, RhCl(PPh₃)₃, can be used for the selective hydrogenation of alkenes. Which statement regarding its mechanism is true? (A) It is an example of a heterogeneous catalyst. (B) The first step in the cycle is the coordination of the alkene to the 16-electron complex. (C) The metal center is oxidized to Rh(III) during the oxidative addition step. (D) The catalyst obeys the 18-electron rule in its resting state. (E) The active species formed in solution is a 14-electron complex RhCl(PPh₃)₂.