Answer:
The correct options are;
a: line AB Is a diameter of circle O is the b: midpoint of AB
Explanation:
Given that the circle with circumscribes the triangle, we have;
The definition of the circle allows either its radius or center to be specified, in this case, the on pint specified is O which would be the center
Given that from the options, we have AO and Ob , therefore, the line AB passes through the center and the correct option is a. line AN is a diameter of circle O is the b. midpoint of AB.