How can i make options unselectable in an ng-dropdown multiselect ?

Question

I bind to a ng-dropdown multiselect, 

 

 <div id="myObj"
                         ng-dropdown-multiselect=""
                         selected-model="myObj"
                         extra-settings="myObjSettings"
                         options="myObjList"
                         translation-texts="myObjCustomText"
                         ng-dropdown-multiselect-disabled="myObjDisabled"
                         events="myObjtEvents"></div>
                </div>
                
The myObjList is a KeyValue pair. How can i make certain options in the list as non-selectable depending on a condition and maybe even strike out the option , ie put a line through it so the user knows it is not selectable ?