Select the option showing correctly the change from Active to Passive voice. The chief taught his tribesmen how to use a short spear.

• A.  The tribesmen were taught how a short spear is used by their chief.
• B.  The tribesmen were taught how to use a short spear by their chief.  
• C.  The tribesmen taught the chief how to use a short spear.
• D.  The tribesmen taught the chief how a short spear is used.