Echo versus Question Mark Equals

> <?php
> include('http://www.your.domain/next_page.php?foo=bar ');

> exit();

      echo '<?php echo $_GET[\'foo\']; ?>';
    } else {
      echo '<?php echo \'Not available\'; ?>';

> <?php
> include('http://www.your.domain/next_page.php?foo=bar ');

> exit();

      echo '<?php echo $_GET[\'foo\']; ?>';
    } else {
      echo '<?php echo \'Not available\'; ?>';

> <?php
> include('http://www.your.domain/next_page.php?foo=bar ');

> exit();

      echo '<?php echo $_GET[\'foo\']; ?>';
    } else {
      echo '<?php echo \'Not available\'; ?>';