Linear Algebra. Write clearly

Problem 1.4 Consider again the problem of merging k sorted length- n arrays into a single sorted length-kn array. Consider the algorithm that first divides the k arrays into k/2 pairs of arrays, and uses the Merge subroutine to combine each pair, resulting in k/2 sorted length- 2n arrays. The algorithm repeats this step until there is only one length-kn sorted array. What is the running time of this procedure as a function of k and n, ignoring constant factors and lower-order terms? a) n log k b) nk c) nk log k d) nk log n e nk2