# e(ecentricity)=__________ for parabola.

$(a)\;1\qquad(b)\;2\qquad(c)\;3\qquad(d)\;4$

The locus of a point which moves in a plane such that the ratio of its distance from a fixed point to its perpendicular distance from a fixed straight line is constant.This constant ratio is known as ecentricity.
e(ecentricity)=1 for parabola.
Hence (a) is the correct answer.