In $\triangle A B C$, the sum of the lengths of two sides is $x$ and the product of those lengths is $y$. If $c$ is the length of its third side and $x^2-c^2=y$, then the circumradius of that triangle is

• Correct answer
  A

  $\frac{\mathrm{c}}{\sqrt{3}}$
• B

  $\frac{c}{3}$
• C

  $\frac{y}{\sqrt{3}}$
• D

  $\frac{3 y}{2}$

Hence, the correct answer is option: 'A'.