Option C:
The measure of ∠1 is 31°.
Solution:
Measure of intercepted arc = 37°
Measure of vertical arc = 25°
If two chords intersect inside a circle, then the measure of the angle formed is one half the sum of the measure of the arcs intercepted by the angle and its vertical angle.
The measure of ∠1 is 31°.
Option C is the correct answer.