Two defective clocks, A and B were set to the same time simultaneously. Clock A lost 2 minutes per hour whereas Clock B gained 1 minute per hour. When the times on the 2 clocks were noted again, they were 1 hour apart. How much time had past?

• A.          20 hours                             
• B.  10 hours
• C.                         5 hours               
• D.         12 hours