You have to ask you teacher to show you which ones you got wrong and the answers to them.
Answer:
C. Mean
Explanation:
Mean = (∑
)/N
Median = central values when data is sorted
Mode = most repeated value
Standard deviation = 
In standard deviation, formula you may see that deviation is being calculated from the mean (central location). But here we take square of the value before adding all of them.
But if we just take
, it would be equal to zero.
<u>EXAMPLE</u>
Take 4, 9, 5 as data
mean = (4+9+5)/3 = 18/3 = 6
sum of deviations from mean = (4-6)+(9-6)+(5-6) = (-2)+(3)+(-1) = 0