A courier company’s charges are based on the distance required to deliver a parcel. Within a radius of `40` km, charges can be determined from a graph like that shown below.

Which one of the following rules could be used to describe this graph?

**A.** `C ={(10 text( for ) \ \ 0 < x < 10),(20 text( for ) 10 < x < 20),(40 text( for ) 20 < x < 40) :}`

**B.** `C ={(10 text( for ) \ \ 0 ≤ x ≤ 10),(20 text( for ) 10≤ x ≤ 20),(40 text( for ) 20 ≤ x ≤ 40) :}`

**C.** `C ={(10 text( for ) \ \ 0 < x ≤ 10),(20 text( for ) 10 < x ≤ 20),(40 text( for ) 20 < x ≤ 40) :}`

**D.** `C ={(10 text( for ) \ \ 0 ≤ x < 10),(20 text( for ) 10≤ x < 20),(40 text( for ) 20 ≤ x < 40) :}`

**E.** `C ={(10 text( for ) \ \ 0 < x < 10),(20 text( for ) 10≤ x ≤ 20),(40 text( for ) 20 < x < 40) :}`