index.php

<?php

// $str1 = '1,2,3,4,5';
// $arr = explode(',',$str1);
// foreach($arr as $i)
// echo($i.'<br>');
$num = 4;
$num2 = 3;
$cars = array
  (
  array("Volvo","first_second_third_fourth","a"),
  array("BMW","hanabi_claude_yi sun shin_granger","b"),
  array("Saab","third_second_third_fourth","c"),
  array("Land Rover","fourth_second_third_fourth","d")
  );
 echo "<form method='POST'>";
for ($x = 0 ; $x<$num; $x++) {
   echo "<p><b>Question".$cars[$x][0]."</b></p>";
      $choices = $cars[$x][1];
      $arr = explode('_',$choices);
      echo "<ol type='A'>";
      foreach ($arr as $id => $value) {
         $y = $id+1;
            echo "<li><input type='radio' name='answer[$x]' value='".chr(64 + $y)."'>$value</li>";
      }
      echo "</ol>";

   echo "<br><br><br>";

}
echo "<input type= 'submit' name='submit' value='Submit'></form>";

if (isset($_POST['submit'])) {
   echo "<pre>";
         var_dump($_POST['answer']);
   echo "</pre>";
}
?>