A structural member under loading has a uniform state of plane stress which is usual notations is given by $\sigma _{x} = 3P, \sigma _{y} = -2P$ and $\tau_{xy} = \sqrt{2}P$, where $P>0$. The yield strength of the material is $350$ $\text{MPa}$. If the member is designed using the maximum distortion energy theory, then the value of $P$ at which yielding starts (according to the maximum distortion energy theory) is

- $70$ $\text{MPa}$
- $90$ $\text{MPa}$
- $120$ $\text{MPa}$
- $75$ $\text{MPa}$