Which defines a circle a. two days with a common endpoint b. a piece of a line with two endpoints c. a piece of a line with one endpoint d. all copland points equidistant from a given point

The correct answer is d.

Step-by-step explanation:

Any point that is co planar with one another and is also equidistant from a given point is a circle. We need it to be co planar, otherwise it would be 3-dimensional and create a sphere. And if they we not all equidistant, they would not make an even circle (it'd be an oval or another shape).