Answer:
B
Explanation:
When looking at the number line, we can see the distance between A and B is one unit
A |-2| + |-1| = 2+1 =3 That is not 1 unit
B 2-1 =1 that is 1 unit
C -2 + -1 = -3 that is not 1 unit
D |-1| - (-2) = 1 + 2 =3 that is not 1 unit
Even though it says all expressions, there is only 1 that shows a distance of 1 unit