With no explanation, label each line with "location-GPE", "O", "other-law", "art-broadcastprogram", "art-film", "art-music", "art-other", "art-painting", "art-writtenart" or "building-airport" preceded by ":".
They
were
produced
in
response
to
silver
agitation
by
citizens
who
were
angered
by
the
Fourth
Coinage
Act
,
which
had
effectively
placed
the
United
States
on
a
gold
standard
.
They:O
were:O
produced:O
in:O
response:O
to:O
silver:O
agitation:O
by:O
citizens:O
who:O
were:O
angered:O
by:O
the:O
Fourth:other-law
Coinage:other-law
Act:other-law
,:O
which:O
had:O
effectively:O
placed:O
the:O
United:location-GPE
States:location-GPE
on:O
a:O
gold:O
standard:O
.:O