Answer: Choice B) 60
Step-by-step explanation:
This is known as a cyclic quadrilateral since all four points are on the circle's edge, and the quadrilateral is entirely inside the circle (no parts of the quadrilateral spill outside the circle). Another term is "inscribed quadrilateral"
Since we have an inscribed quadrilateral, this means the opposite angles of the quadrilateral are supplementary.
B+D = 180
120+x = 180
x = 180-120
x = 60