By the geometric definition of a parabola, which relationship is always true for any point P on the curve?

• A. Distance(P, Focus) = Distance(P, Directrix)
• B. Distance(P, Focus 1) + Distance(P, Focus 2) = constant
• C. Distance(P, Focus) + Distance(P, Directrix) = constant
• D. Distance(P, Vertex) = Distance(P, Focus)

Answer: (A)