Correct Answer - Option 4 : Tabular of trough compass
Magnetic bearing:
The magnetic bearing of a line is the horizontal angel which it makes with the magnetic north. Since magnetic meridian changes gradually with time and thus magnetic bearing also gets changed with time.
The magnetic bearing is determined from either the prismatic compass or from surveyor’s compass.
In order to measure the magnetic bearing of a line, the theodolite should be provided with either a tabular compass or trough compass.
