A parabola is a symmetrical plane curve that has a minimum o maximum point called vertex. Parabolas are the graphs of quadratic functions:
An important property of parabolas is that they have a focus and a directrix, the first being a point and the second being a line. If you take any point from the parabola then its distance to the focus is exactly the same as its perpendicular distance to the directrix. This means that the first option is the correct one.