Each question panel provides you the option to allow students either single or multiple attempts at answering the question. In Edit Mode, select Edit Answer for the question panel you wish to alter. A "Multiple Attempts” check box will appear immediately below the question panel.
Selecting this check box will allow students to attempt the question and check their answer as many times as they wish. Note that this is the default setting for all Lt questions. If you deselect this check box, students will be presented with the following dialog and asked to Commit their answer before seeing the correct answer. The students are made aware that they will not be able to edit their work after committing their answer.