Answer: I would say B is the right option.
Explanation:
Adding in 0 would affect the median, but not by much.
To calculate median: sort numbers in order from least to greatest. The middle number is the median.
*Without 0:*
100, 120, 130, 150 Median: 120 and 130
when there are two medians, add both numbers, then divide the sum by 2.
120+130 = 250
*With 0:*
0, 100, 120, 130, 150 Median: 120
As you can see, the median does decrease from 125 to 120. That's a -5 difference.
Adding in 0 would also change the mean because it adds another number to divide by. To calculate the mean without 0, you'd just add up 100, 120, 130, ans 150 then divide the sum by 4, since there are four numbers. But by adding 0 into the mix, it doesn't change the sum, but adds one more number to divide by. So instead of adding 100, 120, 130, and 150 and dividing the sum by 4, you'd divide by 5, since there are now five numbers because 0 was added.
Lets work out the mean and see what comes up.
*Without 0:*
*With 0:*
Here, the mean decreases from 125 to 100. That's a -20 difference! Hence, B is your answer. :)