In Figure, coefficient of kinetic friction between the 4 kg block and the inclined surface is $\frac{1}{\sqrt{3}}$ . Here 'm' is such a mass that the 4 kg block is moving up the plane with a constant speed, then m is:

• A

  2 kg

• B

  2.8 kg

• C

  3.4 kg

• D

  4 kg