One way, with or without jquery, is something like this.
1) When the submit button is clicked, loop through each row in the table.
2) At each row, use
getElementsByTagName() to get all the
<select>s in that row.
3) Loop through the <select>s in 2) and check that the
selectedIndex of each is > 0
Without jquery, it should be only a handful of lines of code.