A While certiorari can be issued against judicial or quasi-judicial authorities, mandamus can be issued against administrative authorities also.
B Mandamus can be issued for a declaration that an Act is ultra vires the Constitution and certiorari can also be issued for correcting that defect
C Certiorari can be issued against a quasi-judicial authority to prevent it from exercising jurisdiction not vested in it. Mandamus cannot be issued for that purpose.
D Certiorari cannot be issued against usurping a public officer, but Mandamus can be issued for that purpose.
