Answer;
[tex]\text{Ray}[/tex]Explanation;
We can get the correct answer by taking a look at the definitions;
a) An angle is the intersection of two lines and thus will not extend to infinity by itself
b) A circle is a set of points that are equivalent from a given center point
c) Ray; A ray starts up from a point and does not have a definite end. This means we know the start point but we do not know its end point
d) Vertex; This is the edge of a shape where we have two lines or edges meeting