Question 3 1 pts Which of the following statements about the tree produced by Huffman's algorithm, that correspond to an optimal prefix code, are true? There may be more than one correct statement. The tree is constructed from the leaves up. The letter with the highest frequency is at the root of the tree. Every node of the tree corresponds to a letter of the alphabet. If a letter x has higher frequency than a letter y, then x is closer to the root of the tree than y. If a letter x is closer to the root of the tree than a letter y, then x's frequency is either higher or the same as y's frequency