If $a \pm i b$ and $b \pm a i$ are the roots of $x^4-10 x^3+50 x^2-130 x+169=0$, then $\frac{a}{b}+\frac{b}{a}=$

• A

  $\frac{25}{12}$
• B

  $\frac{5}{2}$
• Correct answer
  C

  $\frac{13}{6}$
• D

  $\frac{34}{15}$

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