The average of the first list is 4 and the number deviates from 4 evenly. what I mean by that is, the next set of numbers (2,6) are both 2 away from 4, and the next set after that (0,8) are both 4 away from 4.

To have a similar deviation, we want the next set to look similar.

-1 and 9 will stretch the outer limits of the list, which will increase the standard deviation significantly.
4 and 4 will add too much weight to the center of the list. It'll decrease the standard deviation.
3 and 5 may be right
2 and 6 may be right
0 and 8 will add weight to the outer limits again, and stretch the deviation.

So it's a toss-up between (3 and 5) and (2 and 6). And my educated guess is on 2 and 6 since basically come in right in the center of the previous standard deviation, it should change it the least.

Answer: D