Correct option is (B) 40°
\(\because\) arc AB \(\cong\) arc CD
Since, congruent (equal) arcs subtends equal angle the centre of the circle.
Also, \(\angle AOB\) = Angle subtended by arc AB at centre O
\(\angle COD\) = Angle subtended by arc CD at centre O
\(\therefore\) \(\angle AOB\) = \(\angle COD\) \((\because arc\,AB\cong arc\,CD)\)
\(\Rightarrow\) \(\angle COD\) = \(\angle AOB\) \(=40^\circ\) \((\because\angle AOB=40^\circ(given))\)
