You are declarer(West) - what you would play at trick one
Contract = 4♥
lead = ♠2
Answer is ♠9.
In a suit contract North would lead the ♠K if he had ♠K and ♠Q. Therefore he has probably lead from a suit headed by the ♠K or ♠Q. We should play the ♠9 hoping that North has lead from a high honour plus the ♠10 and we can finesse the high honour later.
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