Where do the 'options' come from? If they are from the command line use Getopt::Long. If they are derived internally (perhaps through a GUI or command line interface) then you could:

use strict;
use warnings;

my %options = map {$_ => 0} qw(one two three);

$options{two} = 1; # Set in some unspecified place

for my $option (grep {$options{$_}} keys %options) {
    print "Option '$option' was used\n";
}
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Prints:

Option 'two' was used
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