Correct option is (B) 125°
\(\because\) A, B, C & D are four points on circle.
\(\therefore\) Quadrilateral ABCD is a cyclic quadrilateral.
We know that sum of opposite angles in a cyclic quadrilateral is \(180^\circ.\)
\(\because\) \(\angle ADC\;\&\;\angle ABC\) are opposite angles in cyclic quadrilateral ABCD.
\(\therefore\) \(\angle ABC+\angle ADC\) \(=180^\circ\)
\(\Rightarrow\) \(\angle ABC\) \(=180^\circ-\angle ADC\)
\(=180^\circ-55^\circ\) \((\because\) \(\angle ADC=55^\circ)\)
= \(125^\circ\)
