The von Mises yield criterion relates the yield stress in uniaxial tension (\( \sigma_t \)) and the yield stress in pure shear (\( \sigma_{sh} \)) using the following formula:
\[
\sigma_t = \sqrt{3} \cdot \sigma_{sh}
\]
where:
\( \sigma_t = 200 \, {MPa} \) (yield stress in uniaxial tension),
\( \sigma_{sh} \) is the yield stress in pure shear.
To find the yield stress in pure shear, we solve for \( \sigma_{sh} \):
\[
\sigma_{sh} = \frac{\sigma_t}{\sqrt{3}} = \frac{200}{\sqrt{3}} \approx 115.5 \, {MPa}
\]
Thus, the correct answer is (A) 115.5 MPa.