Zero Eccentricity
Which conic section has an eccentricity equal to zero?

Hint
The eccentricity,
$$e$$
, of a conic section indicates how close its shape is a circle.
Hint 2
The eccentricity of a parabola is one.
A conic section is a curve obtained from the intersection of a cone’s surface and a flat plane. The eccentricity,
$$e$$
, of a conic section indicates how close its shape is a circle. As eccentricity grows larger, the less the shape resembles a circle. Thus,

Circle