First of all, distance cannot be negative so you eliminate answers A and D immediately.
Now to find the distance between a negative number and a positive number, you either have to take the absolute value of the negative number (to turn it positive) and add it to the positive or take the absolute value of the positive number subtracted by the negative number.
Basically, you're doing this because it compensates for the distance between the negative number and 0.
The only answer choice that is consistent with these terms is B.
