Index: wp-admin/custom-background.php
===================================================================
--- wp-admin/custom-background.php	(revision 23400)
+++ wp-admin/custom-background.php	(working copy)
@@ -301,7 +301,7 @@
 </tr>
 
 <tr valign="top">
-<th scope="row"><?php _e( 'Attachment' ); ?></th>
+<th scope="row"><?php _x( 'Attachment', 'Background image selection: fixed or scroll.' ); ?></th>
 <td><fieldset><legend class="screen-reader-text"><span><?php _e( 'Background Attachment' ); ?></span></legend>
 <label>
 <input name="background-attachment" type="radio" value="scroll" <?php checked('scroll', get_theme_mod('background_attachment', 'scroll')); ?> />