Sixth Answer
When dummy cashed the remaining spade winners, you discarded clubs, leaving this position:
Declarer played a heart to the Jack and your Queen. What now; a heart, a diamond or a club? Declarer has already shown up with Ace-King-Jack of spades, Ace-Jack of hearts, and Ace-King of clubs. That totals 20 HCP, so it looks like partner has the Ace-King-Queen of diamonds. Lead the Jack of diamonds.
The full deal appears on the next page.