The horizontal angle between the true meridian and magnetic at a place is called declination.


- The Earth has a magnetic field that varies from place to place.
- The magnetic north pole and the geographic north pole are not located at the same point on the Earth's surface.
- The angle between the true meridian (geographic north) and the magnetic meridian (magnetic north) at a specific location is known as declination.


- The Earth's magnetic field is generated by the movement of molten iron in its outer core.
- This movement is influenced by various factors such as the rotation of the Earth and the interaction with the Sun's magnetic field.
- As a result, the magnetic field is not perfectly aligned with the Earth's rotational axis, leading to declination.


- Declination is measured in degrees east or west.
- If the magnetic meridian is to the east of the true meridian, the declination is positive (+).
- If the magnetic meridian is to the west of the true meridian, the declination is negative (-).


- Declination is an important parameter for navigation and surveying.
- It is used to convert magnetic bearings to true bearings and vice versa.
- Without considering declination, there can be errors in direction and positioning.


- Magnetic bearing: The direction of a line measured with respect to the magnetic meridian.
- Local attraction: Disturbances in a compass needle caused by nearby magnetic substances or structures.
- Azimuth: The horizontal angle measured clockwise from a reference direction, usually the north.

Therefore, the correct answer is option 'C' - Declination.