Comment Random Issue

Hello,

Am developing a plugin for comment captcha. I have around 5 techniques for captcha and put each technique in separate file. Just consider if the user select the first technique then I will include that particular file, if second technique, then second file will be included
respectively, sample coding below

(eg) if($option==1)
include (‘file1.php’);
if($option==2)
include (‘file2.php’);
.
.
.
if($option==5)
include(‘file3.php’);

Suppose user need to be a random the option value is 6, problem arises.
(eg)
if($option==6)
$option=rand(1,5);
if($option==1)
include (‘file1.php’);
if($option==2)
include (‘file2.php’);
.
.
.
if($option==5)
include(‘file3.php’);

Just consider, if i select the random option and I got random number 1 and the file1 will be loaded and waiting for that captcha, suppose if i enter the wrong captcha value, it will not work and the error throws on another file may be file3.php, but am entering for file1.php modeled captcha value.

Note: If i select any one particular captcha model like model1, then it will work perfect for correct and incorrect results.

Please suggest me