use HTML::Template::Compiled;
my $htc = HTML::Template::Compiled->new(
    scalarref => \"<select><%html_option cities %></select>",
    plugin => [qw(::HTML_Tags)],
);
$htc->param(
    cities => [
      'Hamburg', # selected
      map { [$_, $_] } qw(Berlin Hamburg North_Adams)],
);
print $htc->output;

##</code><code>##

<select><option value="Berlin" >Berlin</option>
<option value="Hamburg" selected="selected">Hamburg</option>
<option value="North_Adams" >North_Adams</option></select>

##</code><code>##

my @cities = qw(Berlin Hamburg North_Adams);
my $htc = HTML::Template::Compiled->new(
    scalarref => \"<select><%html_option cities %></select>",
    plugin => [qw(::HTML_Tags)],
);
$htc->param(
    cities => [
        1, # selected
        map { [$_, $cities[$_]] } 0..$#cities],
);
print $htc->output

##</code><code>##

<select><option value="0" >Berlin</option>
<option value="1" selected="selected">Hamburg</option>
<option value="2" >North_Adams</option></select>