None of the above
1,2,3,4 = 2 comparison Final sorted array
1,2 3,4 = 2 comparison 2nd level
1 2 3 4 Individually sorted elements
Minimum comparison is only possible when 1st and last element of either array are smaller then first element of another
so in such as case at each level we will have n/2 comparisons
In general= n/2 * number of levels
= $\frac{n}{2}log_{2}n$
For n=2 only 1 comparison
For n=4 only 4 Comparison and so on