Making a specific <select> option automatically check and disable check box in another form field
<p>I have a very simple form for uploading a file. In the form, there's a dropdown  menu where you can choose a category for the file you're uploading. I also have another checkbox which is by default unchecked. How can I make it so that if the third  in the dropdown is selected, the checkbox is automatically checked and disabled? Thanks for your help.</p>
