You are declarer(West) - what you would play at trick one
Contract = 5♦
lead = ♣3
- ♠ 4
- ♥ KQ43
- ♦ K9732
- ♣ K105
Answer is ♣5.
The ♣K would be wrong, you should never lead away from an ace in a suit contract, therefore south almost certainly has the ♣A. In this case it won't matter whether you play the ♣10 or the ♣5 but as a matter of form you should get into the habit of playing low when you have a card of equal rank in your own hand.
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