C and D are interchanged in their ranks. C is 5th from the top and D is 10th from the bottom. How many people are there in total?

Answer: C. 16
If C is 5th from the top and D is 10th from the bottom, then total = 5 + 10 - 1 = 14. However, since C and D are interchanged, the total must be 16.