When adjusting a magnetic compass using the fore-and-aft permanent magnets,you should().
- Ause the magnets one at a time,putting one in one side and then one on the opposite side,one step higher
- Buse the magnets in pairs,starting at the top,with trays at the highest point of travel
- Cuse the magnets in pairs,from the bottom up,with the trays at the lowest point of travel
- Dfill all the trays with magnets,then remove them one-by-one until the deviation is removed