For this question, I am getting different answers based on what numbers I choose. The answer key shows that Option A is the correct answer but I am getting multiple answers for eg-
1. Case 1
If area of the bigger square is 16 then side length of bigger square is 4 and diagonal would be √32 which would be 4√2
Since area of smaller square is half of bigger square- 16/2 = 8 so the side length would be 2√2 for smaller square and the diagonal would be 4
Difference in the length is = 4√2-4 which is option A
2. Case 2
If area of the bigger square is 8 then side length of bigger square is 2√2 and diagonal would be 4
Since area of smaller square is half of bigger square- 8/2 = 4 so the side length would be 2 for smaller square and the diagonal would be 2√2
Difference in the length is = 4-2√2 which doesn’t match with any here
So, where am I going wrong? 
