Answer: D. 14
Explanation:
To get the median, first, you have to sort all the numbers from least to greatest:
(13, 11, 10, 18, 17, 16, 15, 12, 11, 16, 14, 12, 17) --->
(10, 11, 11, 12, 12, 13, 14, 15, 16, 16, 17, 17, 18)
Second, remove the first 6 numbers and the last 6 numbers.
(10, 11, 11, 12, 12, 13, 14, 15, 16, 16, 17, 17, 18)
and you'll get
(14)
Therefore, D. 14 is your answer.
Let me know if this helps :)