Choose A, B, C, or D to indicate the sentence that best combines each pair of sentences in the following questions: You can learn a lot about American history. Make sure you visit the exhibition tomorrow.

• A. 
  You can learn a lot about American history if you visit the exhibition tomorrow.
• B. 
  You can’t learn a lot about American history in case you visit the exhibition tomorrow.
• C. 
  You can’t learn a lot about American history provided you visit the exhibition tomorrow.
• D. 
  You can learn a lot about American history unless you visit the exhibition tomorrow.