With no explanation, label each line with "location-GPE", "O", "art-broadcastprogram", "art-film", "art-music", "art-other", "art-painting", "art-writtenart", "building-airport" or "building-hospital" preceded by ":".
Although
historical
records
provide
limited
detail
on
the
German
decision
to
pursue
the
heavy
water
approach
,
it
became
clear
after
the
war
that
they
had
explored
that
option
.
Although:O
historical:O
records:O
provide:O
limited:O
detail:O
on:O
the:O
German:location-GPE
decision:O
to:O
pursue:O
the:O
heavy:O
water:O
approach:O
,:O
it:O
became:O
clear:O
after:O
the:O
war:O
that:O
they:O
had:O
explored:O
that:O
option:O
.:O