How many interfaces can a Cisco ASA bridge group support and how many bridge groups can a Cisco ASA appliance support?
A. up to 2 interfaces per bridge group and up to 4 bridge groups per Cisco ASA appliance
B. up to 2 interfaces per bridge group and up to 8 bridge groups per Cisco ASA appliance
C. up to 4 interfaces per bridge group and up to 4 bridge groups per Cisco ASA appliance
D. up to 4 interfaces per bridge group and up to 8 bridge groups per Cisco ASA appliance
E. up to 8 interfaces per bridge group and up to 4 bridge groups per Cisco ASA appliance
F. up to 8 interfaces per bridge group and up to 8 bridge groups per Cisco ASA appliance
Old answer, see:
https://www.cisco.com/c/en/us/td/docs/security/asa/asa97/configuration/general/asa-97-general-config/intro-fw.html#id_37129
And you will find that version 8.4(1) supported up to 8 bridge groups and 4 interfaces in each.
Starting from version 9.3(1) it has been increased from 8 to 250 supported bridge groups with each supporting 4 interfaces as before.