If adjacency matrix is used, then what is the time complexity of BFS algorithm?a.O(e)b.O(n+e)c.Od.O(n2)

The time complexity of BFS (Breadth-First Search) algorithm using an adjacency matrix is O(n^2). Here's why:

1. Initialization: Before the BFS algorithm starts, it initializes all vertices as not visited, which takes O(n) time.

2. Traversal: The BFS algorithm traverses all vertices of the graph. For each vertex, it needs to scan its entire row in the adjacency matrix to find its adjacent nodes. Since the adjacency matrix is a n*n matrix (where n is the number of vertices), this step takes O(n) time for each vertex.

3. Total time complexity: Since the BFS algorithm needs to do the above step for all n vertices, the total time complexity is O(n*n) = O(n^2).

So, the correct answer is d. O(n^2).