To determine the order in which nodes are visited during a Breadth-First Search (BFS) starting from node 0, let's go through the process step by step.

BFS Process:

1. Start at node 0: Node 0 is the starting point, so it's the first node visited.
2. Visit neighbors of node 0: The neighbors of node 0 are nodes 1, 3, and 4. Since BFS explores nodes level by level, and neighbors are visited in numerical order, node 1 is visited first, followed by node 3 and then node 4.
3. Visit neighbors of node 1: Node 1 has neighbors 0, 4, and 5. Node 0 has already been visited, so we visit the next unvisited node in numerical order, which is node 5.
4. Visit neighbors of node 3: Node 3 has neighbors 0 and 4. Both have already been visited, so no new nodes are visited at this step.
5. Visit neighbors of node 4: Node 4 has neighbors 1, 2, 3, and 0. Nodes 1, 3, and 0 have already been visited, so the next unvisited node in numerical order is node 2.
6. Visit neighbors of node 5: Node 5 has neighbors 1 and 4. Both have already been visited.

Conclusion:

The BFS order is 0, 1, 3, 4, 5, 2.

So, the correct choice is Choice 3: 0, 1, 3, 4, 5, 2.

Would you like more details or have any other questions? Here are some related topics:

1. How does BFS ensure the shortest path in unweighted graphs?
2. What is the difference between BFS and Depth-First Search (DFS)?
3. How would the BFS order change if we start from a different node?
4. What is the time complexity of the BFS algorithm?
5. How can BFS be modified for different traversal orders?

Tip: In BFS, always remember that nodes are visited level by level, and the order of visiting neighbors can affect the final traversal order.