fix bug

apps/exams/Lib/Model/ExamsPaperModel.class.php

@@ -45,7 +45,7 @@ class ExamsPaperModel extends Model
             $map['_string'] .= ' AND attachment > 0';
         }
         if ((int)$isApi === 3) {
-            $this->selectAdd('( SELECT exams_paper_id from el_exams_paper_options WHERE el_exams_paper_options.exams_paper_id =  el_exams_paper.exams_paper_id) as abc');
+            $this->selectAdd('( SELECT count(el_exams_paper_options.exams_paper_id) from el_exams_paper_options WHERE el_exams_paper_options.exams_paper_id =  el_exams_paper.exams_paper_id) as abc');
         }