Find the resultant of three vectors $\overrightarrow{\mathrm{OA}},\overrightarrow{\mathrm{OB}}\mathrm{and}\overrightarrow{\mathrm{OC}}$ shown in the following figure. Radius of the circle is R.

• A

  2R

• B

  $\mathrm{R}(1+\sqrt{2})$

• C

  $\mathrm{R}\sqrt{2}$

• D

  $\mathrm{R}(\sqrt{2} -1)$