Steel machine element at the critical section is in biaxial stress state with two principal stress being 300 $$\frac{N}{mm^{2}}$$ and 300 $$\frac{N}{mm^{2}}$$ (equal magnitude). Find the von Mises stress (in $$\frac{N}{mm^{2}}$$) in the member

A

212.1

B

600

C

424.2

D

300