Final answer:
Option C, ce = a, must be true for the given band.
Step-by-step explanation:
In order to determine which statement must be true for the given band, we need to evaluate each option. Let's analyze each statement:
A. ac
B. -a e c
C. ce = a
D. -c = d
After evaluating each statement, we find that option C, ce = a, must be true for the given band.