The answer would be C. ADB:310 degrees.
A major arc includes 3 points. So that eliminates answer choices B and D.
Angle ACB is a central angle and intercepts the arc AB. The measure of the central angle and the arc it intersects have the same measure. Meaning that Arc AB equals to 50 degrees.
A circle is equal to 360 degrees. So subtract the measure of the minor arc to 360 to get the measure of the major arc.
360-50=310.
Making arc ADB equal 310 degrees