Rachel Has Been Reading Her Physics Book $\times$ 10³ N

Rachel has been reading her physics book.She takes her weighing scales into an elevator and stands on them.If her normal weight is 690 N (155 lbs) ,and the elevator moves upward at 0.25g and then down at 0.25g,what is the difference between the up and down scale readings?

A) 690 N
B) 520 N
C) 170 N
D) 345 N
E) 1.04 $\times$ 10³ N