AC voltage can be raised or lowered easily by a transformer. (D)
A). AC is not necessarily any safer than DC.
B). The only reason most appliances run directly on AC, and few run on DC, is because AC has been so widespread for so long that THAT's what everybody has coming out of the outlets in their house, and so THAT's the way manufacturers BUILD the appliances. If they BUILT appliances to run on DC, they would only sell a few, to people who spend a lot of time traveling in their mobile campers, but not to anybody who needs appliances for their home.
C). The current that flows INTO a transformer depends on how much current is being taken OUT of it, and the current being taken OUT of it depends on the voltage at the output, and on how many people have how many things connected to the output of the transformer.