When adjusting a magnetic compass using the fore-and-aft permanent magnets, you should __________.

A
use the magnets one at a time, putting one in one side and then one on the opposite side, one step higher.
B
use the magnets in pairs, starting at the top, with trays at the highest point of travel
C
use the magnets in pairs, from the bottom up, with the trays at the lowest point of travel
D
fill all the trays with magnets, then remove them one-by-one until the deviation is removed
E