Ans D
1.For worst case take these two list
A- 10,20,30,40 & B-11,21,31,41
When we apply merge algo on these two list then element get sorted alternatively from these lists.
1.compare 10&11-10
2.compare 20&11-11
3.compare 20&21-20
4.compare 30&21-21
5. compare 30&31-30
6. compare 40&31-31
7. compare 40,41-40
& last 41
Sorted list will be - 10,11,20,21,30,31,40,41
Total comparison= m+n-1=4+4-1=7
2. Best Case - In this case elements of one list get sorted first by comparing and for sorting remaining elements of second list needs no comparison because they are already sorted.
A= 10,20 B-30,40,50,60,70
1.Compare 10&30-10
2.Compare 20&30-20
and then no comparison for 30 40 50 60 70
Total comparison=min(m,n)=min(2,5)=2