The correct answer is D. All the above.
A helical spring is a wire wound in spiral form. The pitch of a close coil spring is very small. The angle made by the coil with horizontal is called the angle of helix.
A helical spring is a mechanical device that stores energy when it is compressed or stretched. It is made up of a wire that is wound in a spiral shape. The pitch of a helical spring is the distance between the coils of the spring. The angle of helix is the angle between the coils of the spring and the horizontal.
Helical springs are used in a variety of applications, including shock absorbers, doorstops, and suspension systems. They are also used in some types of toys and games.