Which, if any, of the following taxes are proportional (rather than progressive)? a. Federal corporate income tax. b. Federal employment taxes (i.e., FICA, FUTA). c. Federal estate tax. d. Federal...

Which, if any, of the following taxes are proportional (rather than progressive)? a. Federal corporate income tax. b. Federal employment taxes (i.e., FICA, FUTA). c. Federal estate tax. d. Federal gift tax. e. All of the above.