In the figure above, triangle ABC is inscribed in the circle with center O and diameter AC. If AB=AO, what is the degree measure of∠ABO?
(A) 15°
(B) 30°
(C) 45°
(D) 60°
![In the figure above triangle ABC is inscribed in the circle with center O and diameter AC If ABAO what is the degree measure ofABOA 15B 30C 45D 60 class=](https://us-static.z-dn.net/files/d66/041643d207f0c68ae42a015f658413c8.jpg)