The correct answer is: B. Catenary
A catenary is the curve that an idealized hanging chain or cable assumes under its own weight when supported only at its ends. The catenary is the shape of a free-hanging cable under uniform tension. It is also the shape of a chain suspended from two points, and of a uniform rod supported at its ends and loaded with equal weights at equal intervals along its length.
A parabola is a conic section that is formed when a plane intersects a cone at an angle that is not parallel to the base of the cone. The parabola is the shape of a mirror that reflects light in a single direction, and of the path of a projectile that is launched at an angle to the ground.
A cycloid is a curve traced by a point on a circle as it rolls along a straight line. The cycloid is the shape of the teeth on a gear, and of the path of a point on a wheel as it rolls along a flat surface.
An ellipse is a conic section that is formed when a plane intersects a cone at an angle that is parallel to the base of the cone. The ellipse is the shape of an egg, and of the orbit of a planet around the sun.