The preorder traversal sequence of a binary search tree is
$25, 15, 10, 4, 12, 22, 18, 24, 50, 35, 31, 44, 70, 66, 90$
Which one of the following is the postorder traversal sequence of the same tree?
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$4, 12, 10, 18, 24, 22, 15, 31, 44, 35, 66, 90, 70, 50, 25$
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$4, 10, 12, 15, 18, 22, 24, 25, 31, 35, 44, 50, 66, 70, 90$
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$90, 70, 66, 50, 44, 35, 31, 25, 24, 22, 18, 15, 12, 10, 4$
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$4, 12, 10, 18, 24, 15, 22, 31, 44, 50, 66, 90, 70, 35, 25$