A box of mass 1 kg is pulled through 1 m along a level floor by a horizontal force of 8 N. The box is then raised vertically on to a bench 2 m high. If g = 10 ms^-2,the total work done on the box is

• A

  18J

• B

  28J

• C

  8J

• D

  $\sqrt{8^2+{20}^2}\mathrm{J}$