What is the trivial lower bound for the following problems?

What is the trivial lower bound for the following problems?

a. Generating all the subsets of an n-item set.b. Sorting an array of n items.c. Finding the largest element in an unsorted array.d. Multiplying two n x n matrices.e. Checking whether n given real numbers are distinct.f. Checking the adjacency matrix of a graph to determine if it is complete.