Which type of nuclear power reactor is used in only 1 percent of all power plants?
pressurized water reactor
boiling water reactors
breeder reactors
reproduction reactors

I believe the correct answer from the choices listed above is the third option. The type of nuclear power reactor that is used in only 1 percent of all power plants would be Breeder reactors. It  is a nuclear reactor that generates more fissile material than it consumes.
Hope this answers the question. Have a nice day.