angle XYZ is an inscribed angle and arc XZ is the arc it intercepts
If you didn't know the measure of an inscribed angle is equal to half the measure of its arc it intercepts or an intercepted arc equals twice the measure of its inscribed angle
∠XYZ is an inscribed angle. The rule is that an inscribed angle is half the measure of its intercepted arc. That means that arc XZ is twice 36, or 72, choice C.
