What is different between AT and ATX power supplies?

• A. They are identical except for their shape.
• B. AT supplies use a single P1 power connector while ATX uses P8 and P9
• C. AT supplies use P8 and P9 power connectors while ATX uses a single P1 connector.
• D. AT power supplies run on 120V AC current while ATX uses 220V AC
• E. None of these