The option to generate a report for the Multi Select Question is pretty simple. To generate a report, you need to navigate to the Results section in the Campaign that you have set up Multi-Select.
Next, you need to choose the Question set up in the campaign.
After selecting the question, the option to select the choices will appear in the Result section under the filters. You may choose multiple options here based on your requirements. Once done, you may click "Filter Results" and Export Results to filter results for these options and export them into a CSV file.