Had I known how crowded it’d be,  I’d never have moved to Madrid.  

A Since it was so crowded in Madrid, I decided that I would never move there.

B I moved to Madrid only because I was unaware of how many people were there.

C In the end, Madrid turned out to be far more crowded than I'd thought before moving there.

D I would have had a better time living in Madrid if only there hadn't been so many people.