Firstly, we will need to try the following options one after the other in order to ascertain our answer
The first option
To find the distance between two points
Distance = Higher number - Lower number
-3 - 20
= - 23
This is very wrong because it has a negative sign
The second option
7 - (-16)
In mathematics, - x - = +
7 + 16
7 + 16 = 23
The answer is OPTION B