Answer:
D. arc RA
Explanation:
A minor arc is one that measures less than 180°.
Application
In the circle shown, arc RA is shown as having a measure of 142°. This is less than 180°, so arc RA is a minor arc.
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Additional comment
A minor arc can be named by its end points. When the major arc with the same end points is being referred to, usually another point on the arc is included in the name. That is, arc AWR and arc RA both have end points R and A. Arc AWR is the major arc with those end points.