A, B, C are the angles in a triangle $\cot A,\cot B,\cot C$ are the roots of $x^3-{\lambda }_1{x}^2+{\lambda }_{2}x-{\lambda }_3=0$ then

• A

  ${\lambda }_2=0$

• B

  ${\lambda }_2=1$

• C

  ${\lambda }_3=-1$

• D

  ${\lambda }_3=1$