A long cylindrical conductor of radius 3cm carries a steady current of 15A uniformly across its cross-section. A coaxial cylindrical hole of radius 1cm is drilled along the axis and left empty. What is the current enclosed by a circular Amperian path of radius 0.5cm that lies entirely inside the hollow region?
a) 2.5A
b) 5A
c) 0A
d) 0.42A