Which of the following options correctly conveys the meaning given in the two sentences? He doesn't have a computer. He knows how to use it.

• A.  He knows how to use a computer and he doesn't have one.
• B.  Although he doesn't have a computer, he knows how to use one.
• C.  Because he doesn't have a computer, he knows how to use one.  
• D.  Because he knows how to use a computer, he doesn't have one.