If an angle is given, name the arc it makes. if an arc is given, name its central angle.

Angles are named with 3 letters with the vertex listed in the center to go from angle to arc name take the first and last letter from the angle to name it.

For arc to angle insert the letter of the center in between the listed arc endpoints. 

Ex1: Angle ABC is are AC 

Ex2: Arc DF with center X is angle DXF

Try a or d, hope that