Solution

The correct answer is option 3

Key Points

• To construct a Huffman tree, the following steps are followed in a specific sequence:
• Step 1: Create leaf nodes (B) - Each character with its frequency is represented as a leaf node.
• Step 2: Build priority queue (C) - The leaf nodes are inserted into a priority queue (min-heap) based on their frequencies.
• Step 3: Combine lowest frequency nodes (D) - The two nodes with the lowest frequencies are combined to form a new node, and the sum of their frequencies is assigned to it. This new node is reinserted into the priority queue.
• Step 4: Repeat until root formed (A) - Steps 2 and 3 are repeated until only one node (the root) remains in the priority queue, which represents the Huffman tree.

Additional Information

• The priority queue ensures that the nodes with the smallest frequencies are always selected first for combination, which is essential for constructing the optimal Huffman tree.
• The Huffman tree is used in data compression algorithms to assign variable-length binary codes to characters based on their frequencies, resulting in efficient encoding.

Sequence: B (Create leaf nodes) → C (Build priority queue) → D (Combine lowest frequency nodes) → A (Repeat until root formed)

Hence, the correct answer is: option 3