If we consider strictly Kruskal's algorithm , then we require sorting of edges and if we consider the worst case,
Quicksort will give = O(E2) [Considering the worst case of quicksort and the fact that we need sorting of edges in Kruskal's algo]
Heapsort will give = O(ElogE)
Substituting E = 16 we have ,
using quicksort we have : 162 = 256
and using heapsort = 16 log 16 = 64
Hence change in time = 256 - 64 = 192 time units