Answer: B
(a) True. ref:http://www.geeksforgeeks.org/dynamic-programming-set-24-optimal-binary-search-tree/
(b) False. ref: https://www.quora.com/Why-is-DFS-preferred-for-finding-connected-components-in-directed-graphs
BFS and DFS both algorithm are used to find connected component. For example: In BFS, a search that begins at some particular vertex 'v' will find the entire connected component containing v (and no more) before returning. To find all the connected components of a graph, loop through its vertices, starting a new breadth first search whenever the loop reaches a vertex that has not already been included in a previously found connected component. For example:If we do the breadth first traversal of the above graph and print the visited node as the output, it will print the following output. “A B C D E F”. The BFS visits the nodes level by level, so it will start with level 0 which is the root node, and then it moves to the next levels which are B, C and D, then the last levels which are E and F.
In BFS, a search that begins at some particular vertex v will find the entire connected component containing v (and no more) before returning. To find all the connected components of a graph, loop through its vertices, starting a new breadth first search whenever the loop reaches a vertex that has not already been included in a previously found connected component.
(c) True. because: inorder is needed
(d) True. ref: https://www.quora.com/Why-is-DFS-preferred-for-finding-connected-components-in-directed-graphs