Each panel is made up of a panel div which contains a panel-heading div for the title, and then a panel-body div for the body.
Inside the panel-heading is the question mark image, and the title inside an a tag. The panel-heading div, the img and the a all have a data-toggle set to an index number - for any given panel all three items have the same data-toggle number. The img and the a tags need the same data-toggle or they won’t expand the body if you don’t click directly on them.
Also when you click on a given heading, the code goes thru all other bodies and collapses them - so that as you expand one panel, any other open panel will collapse.