As West, neither side vulnerable, you hold:
RHO opens 2, raised to 4 as shown. What is your opening lead?
Trick one goes as shown. What is the location of the high diamonds?
Partner has the KQ (maybe the ace, too).
Partner has the KQ, declarer is holding up the ace.
Partner has the K, declarer has the AQ.
Partner has the AK, declarer has the Q.
Partner continues with the A as shown:
Then comes a 3rd round of diamonds, declarer trumping with the Q as shown. And you?
K and another spade.
K and a heart.
K and a club.