As C is the centre of the circle above, so $$\mathrm{AC}=\mathrm{BC}=$$ radii of the circle which implies $$\angle \mathrm{BAC}=\angle \mathrm{ABC}=50^{\circ}$$ (In a triangle when sides are equal, the opposite angles are also equal)



As sum of the angles of a triangle is 180 degrees, in triangle $$A B C$$, we get $$\angle \mathrm{BAC}+\angle \mathrm{ABC}+\angle \mathrm{ACB}=50^{\circ}+50^{\circ}+\angle \mathrm{ACB}=180^{\circ} \Rightarrow \angle \mathrm{ACB}=180^{\circ}-100^{\circ}=80^{\circ}$$

Hence the angle subtended by the minor arc AB at the centre C i.e. $$\angle \mathrm{ACB}=80^{\circ}$$, so the answer is (B).