Note: You are currently viewing documentation for Moodle 2.3. Up-to-date documentation for the latest stable version is available here: question/type/gapselect.
This is very similar to the Drag and drop into text question type, but uses drop-down menus in the text instead of drag-boxes. This works well where the question text is very long, so you would have to scroll a lot to do drag and drop.
This is a question type created and maintained by the Open University.
More http://labspace.open.ac.uk/mod/oucontent/view.php?id=470268§ion=5.4.6 documentation is available on the Open University's OpenLearn site.