Which is the definition of hyperbola?

A)it is a locus of points that is equidistant from a fixed point called center.

B)It is a locus of points such that the sum of its distance from two fixed points (foci) is constant.

C)It is a locus of points such that its distance from focus plus its distance from a directrix is constant.

D)It is a locus of points such that the difference of each point's distances from two fixed points is constant.