Vulnerable against non-vulnerable opponents, you (South) arrive in 4♠ on this auction:
West leads the ♥6 and East wins the king. On the ♥A, West discards a low club, and when East plays a third heart, you ruff as West pitches a low diamond.
After drawing trumps in two rounds, you play a low club toward dummy. West plays low, and you face the critical point in the play. Should you play the king or the jack? Is this just a random guess or is there some clue that suggests playing one honor versus the other?