Ampere's Law: a Very Long, Hollow, Thin-Walled Conducting Cylindrical Shell

Ampere's law: A very long, hollow, thin-walled conducting cylindrical shell (like a pipe) of radius R carries a current along its length uniformly distributed throughout the thin shell. Which one of the graphs shown in the figure most accurately describes the magnitude B of the magnetic field produced by this current as a function of the distance r from the central axis?

A) 1
B) 2
C) 3
D) 4
E) 5