fix: 兼容两种模式的选项格式，显示正确的A,B,C,D

resources/views/components/exam/paper-body.blade.php

@@ -222,7 +222,12 @@
                     <div class="{{ $optionsClass }}">
                         @foreach($options as $optIndex => $opt)
                             @php
-                                $label = chr(65 + (int)$optIndex);
+                                // 兼容两种格式：数字索引 (0,1,2,3) 或字母键 (A,B,C,D)
+                                if (is_numeric($optIndex)) {
+                                    $label = chr(65 + (int)$optIndex);
+                                } else {
+                                    $label = strtoupper($optIndex);
+                                }
                                 // 对LaTeX公式中的特殊字符进行HTML实体编码，防止被浏览器当作HTML标签处理
                                 $encodedOpt = htmlspecialchars($opt, ENT_QUOTES | ENT_HTML5, 'UTF-8');
                                 $renderedOpt = $mathProcessed ? $encodedOpt : \App\Services\MathFormulaProcessor::processFormulas($encodedOpt);