An angle formed by two radii of a circle, such that its vertex is at the center of the circle, is called a(n) angle. a. vertical b. intercepted c. inscribed d. central

It would be a D. Central angle 
It would be a central angle because central angles are formed with two radii and the vertex of a central angle is always at the center of a circle.

72 is the mode because it shows up the most number of times