Which tree traversal strategy visits all nodes level by level?

Breadth-First Search (BFS) is a tree traversal strategy that explores all the nodes level by level. It starts at the root node and explores all nodes at the present depth level before moving to nodes at the next depth level. BFS uses a queue data structure to manage the nodes for exploration. It is often used in scenarios where the shortest path or closest node is needed. Option A (Preorder traversal) is incorrect because it visits nodes in the order: root, left subtree, and right subtree. Option B (Postorder traversal) is incorrect because it visits nodes in the order: left subtree, right subtree, and root. Option C (Inorder traversal) is incorrect because it visits nodes in the order: left subtree, root, and right subtree. Option E (Depth-First Search) is incorrect as DFS explores as far down a branch as possible before backtracking, making it a different traversal approach from BFS.