Beacon allows you to specify an exact number of values (i.e., answer options) that must be selected for a valid response to a question.
Note: If your question will also contain an exclusive answer option, see the instructions in: Setting an Exact Number of Values for a Valid Response With an Exclusive Option (setup requires use of the XML editor).
First, add the (multi-select) question and answer options. In the general options for the element, click on the "More Options" dropdown menu and select "Exactly."
The "exactly" option will appear in the general options for the element. Enter an integer in the field provided. In our example we want the respondent to select 3 responses for our multi-select question, so we entered the number 3 in the text field.
To test, choose "Test Survey" in the actions menu. Locate the question and attempt to select a different number of values than is required and continue. The question will display an error message similar to the example shown below. When the correct number of answer options is selected you will be able to continue to the next question.