Three coplanar forces acting in different direction upon a particle keep it in equilibrium. One of the forces has a magnitude of 10 N and acts towards North. The second force acts towards South-West. What should be the magnitude of the third force if it acts towards East.

A

5 N

B

$$\frac{10}{\sqrt{2}}$$ N

C

10 N

D

$$10\sqrt{2}$$ N