challenge: Who did Alexander Gordon, Lord Rockville, marry in 1769?
  
  A. Anne, daughter of William Duff and widow of the 5th Earl of Dumfries
  B. Anne, daughter of William Duff and widow of the 4th Earl of Dumfries
  C. Lady Anne, daughter of the Earl of Dumfries
  D. Lady Elizabeth, daughter of the Duke of York
  Answer: 