I've updated your code, please have a try.
function test(executionContext) {
var formcontext=executionContext.getFormContext();
var field = formcontext.getControl('new_ttoptionset');
var lookupObj = formcontext.getAttribute('new_divisionlookup');
var lookupObjValue = lookupObj.getValue();//Check for Lookup Value
if (lookupObjValue != null) {
var lookupRecordGuid = lookupObjValue[0].id;
Xrm.WebApi.online.retrieveRecord("account", lookupRecordGuid, "?$select=new_classname2,new_classname3,new_classname4").then(
function success(result) {
var new_classname2 = result["new_classname2"];
var new_classname3 = result["new_classname3"];
var new_classname4 = result["new_classname4"];
formcontext.getAttribute('new_cname1').setValue(new_classname2);
formcontexte.getAttribute('new_cname2').setValue(new_classname3);
formcontext.getAttribute('new_cname3').setValue(new_classname4);
if (field == null || field != null) {
var new_classname222 = formcontext.getAttribute('new_cname1').getValue();
var new_classname223 = formcontext.getAttribute('new_cname2').getValue();
var new_classname224 = formcontext.getAttribute('new_cname3').getValue();
var obj1 = {};
obj1['text'] = new_classname222;
obj1['value'] = 10;
field.addOption(obj1);//add to option set field
var obj2 = {};
obj2['text'] = new_classname223;
obj2['value'] = 11;
field.addOption(obj2);//add to option set field
var obj3 = {};
obj3['text'] = new_classname224;
obj3['value'] = 12;
field.addOption(obj3);//add to option set field
}
},
function (error) {
Xrm.Utility.alertDialog(error.message);
}
);
}
else
var lookupObjValue111 = formcontext.getAttribute('new_cname1').setValue(null);
var lookupObjValue122 = formcontext.getAttribute('new_cname2').setValue(null);
var lookupObjValue133 = formcontext.getAttribute('new_cname3').setValue(null);
}