A \[\sqrt{2}a^2b^2/(a^2+b^2)\] B \[2a^2b^2/(a^2+b^2)\] C \[a^2b^2/(a^2+b^2)\] D \[2\sqrt{2}a^2b^2/(a^2+b^2)\] E \[4a^2b^2/(a^2+b^2)\]