C) Conservative approach – clone the folder, verify it, check in, observe , then schedule to remove obsolete folder.
** Caveat – Before removal, everyone needs to know the old folder is obsolete and not to be used.
** Caveat – history lost
 it can take months to uncover a problem induced by the renaming.
D) The tortise “rename” is convenient but potentially dangerous. Usually works. Acceptable on unimportant svn folders. Use your judgement.