Traversal of a graph is different from tree becausea)There can be a loop in graph so we must maintain a visited flag for every vertexb)All of the mentionedc)BFS of a graph uses queue, but a time efficient BFS of a tree is recursived)DFS of a graph uses stack, but inorder traversal of a tree is recursive

The traversal of a graph is different from a tree due to several reasons:

a) In a graph, there can be a loop, so it's necessary to maintain a visited flag for every vertex. This is to prevent the traversal from going into an infinite loop. In a tree, there's no loop as it's a hierarchical structure.

b) All of the mentioned reasons contribute to the difference in traversal between a graph and a tree.

c) Breadth-First Search (BFS) of a graph uses a queue data structure. This is because BFS explores all the vertices of a graph at the current level before moving on to the vertices at the next level. However, a time-efficient BFS of a tree is recursive because a tree has a specific top-down structure that allows for recursion.

d) Depth-First Search (DFS) of a graph uses a stack data structure. This is because DFS explores as far as possible along each branch before backtracking. But the inorder traversal of a tree is recursive. This is because inorder traversal first explores the left subtree, then the root, and finally the right subtree. This pattern naturally lends itself to a recursive approach.