The coordinate axes are rotated about the origin in the counter clockwise direction through an angle $60^{\circ}$. If $a$ and $b$ are the intercepts made on the new axes by a straight line whose equation referred to the original axes is $x+y=1$, then $\frac{1}{\mathrm{a}^2}+\frac{1}{\mathrm{~b}^2}=$

• Correct answer
  A

  $2$
• B

  $3$
• C

  $4$
• D

  $6$

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