Correct Answer - Option 3 : the angle between the true meridian and the magnetic meridian at a place
Explanation:
Magnetic Declination:
(i) It is quite a common phenomenon that the magnetic meridian and the true meridian at a place generally do not coincide.
(ii) The horizontal angle which the magnetic meridian makes with the true meridian is called as magnetic declination (also sometimes referred as declination).
Negative Declination:
(i) When magnetic north lies towards the west of true north, then the declination is said to be negative.
Positive Decilination:
(i) If the magnetic north lies towards the east of true north, then declination is said to be positive.