The article says:
Most of these young people are ages 16 and up. They work at polling sites. That's where voters cast their ballots during elections. Poll workers check in voters. They show them how to use voting machines, too.
This passage helps the reader to understand __________.
A.why poll workers must be old enough to vote
B.about polling places and poll workers
C.about how to use a voting machine
D.why more poll workers were needed