How would I use JS to select the <option> dynamically?

Basically I have a class (java) that dynamically pulls a list from a database, puts it in <option> tags and spits it back to my jsp file, so I need to set which one is selected after they've been displayed, but need to do it without touching the html, cause i can't.

This make sense?

basically after the select is created i want to set the selected option.

Thanks in advance.