If $A=\left[\begin{array}{ll}a & b \\ b & a\end{array}\right]$ and $A_2=\left[\begin{array}{ll}\alpha & \beta \\ \beta & \alpha\end{array}\right]$, then

• A

  $\alpha=2 a b, \beta=a^2+b^2$
• B

  $\alpha=\mathrm{a}_2+\mathrm{b}_2, \beta=\mathrm{ab}$
• Correct answer
  C

  $\alpha=a^2+b^2, \beta=2 a b$
• D

  $\alpha=a^2+b^2, \beta=a^2-b^2$

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