Choose A, B, C, or D to indicate the sentence that best combines each pair of sentences in the following questions: I had just arrived home. I was called immediately back to the head office 10 kilometers away. 

• A. 
  Hardly had I arrived home when I was called immediately back to the office 10 kilometers away.
• B. 
  Because I had just arrived home, I was called immediately back to the office 10 kilometers away.
• C. 
  Should I had just arrived home, I was called immediately back to the office 10 kilometers away. 
• D. 
  Whenever I had just arrived home, I was called immediately back to the office 10 kilometers away.