I think you are asking about the SELECTED modifier to the OPTION tag. Don't hard code it, however, because it may change. Use a simple test to see whether or not to include it. In the example below, the variable $color has already been set. Note that is $color does not match anything, the browser will show the first OPTION as the selected one.

@colors = ("red", "blue", "green", "cyan");
print "<SELECT NAME=\"MyColor\">\n";
for $x (@colors) {
  printf "<OPTION%s>$x", $color eq $x ?  " SELECTED" : "";
}
print "</SELECT>\n";
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