Which of the following variations in magnetic declination are correctly paired with their respective causes?
1) Diurnal variation - Temperature variation may cause this type of variation
2) Secular variation - Earthquakes may cause this type of variation
3) Irregular variation - Magnetic storms may cause this type of variation
1
1, 2 and 3
2
Only 1 and 2
3
Only 2 and 3
4
Only 1 and 3