Please answer the following multiple choice questions and provide a written explanation for each answer.

1 representation of general trees is (left-first, depth-first) traversal of the tree in which every node is visited twice: first a preorder visit, on which occasion the node itself is appended to the sequence representing the tree; and later a postorder visit, on which occasion a special symbol, say', is appended to the sequence, indicating that the node's child list has come to an end. Using this scheme, the tree B C D is represented by the secuence a. A B C)ER)) D b. A B CE R) D ) C, A B ) C ) E ) R ) D ) ) d A ) B ) C ) D ) E ) R) e. A B CER)D f. A BCE))R) D g. none of the above