Answer:
Using a lil common sense bcz I have no book sense on this...
Step-by-step explanation:
Cobalt (Co) - 1
Germanium (Ge) - 4
Yttrium (Y) - 2
Neodymium (Nd) - 3
I Just looked at which comes before which in the periodic table and obv the one with less length from (1-4) is the lowest in the periodic table continuing... yah digg... lol