A long straight wire of circular cross-section (radius $$a$$) is carrying steady current I. The current I is uniformly distributed across this cross-section. The magnetic field is

inversely proportional to $$r$$ in the region $$r < a$$ and uniform throughout in the region $$r > a$$

directly proportional to $$r$$ in the region $$r < a$$ and inversely proportional to $$r$$ in the region $$r > a$$

Zero in the region $$r < a$$ and inversely proportional to $$r$$ in the region $$r > a$$

uniform in the region $$r < a$$ and inversely proportional to distance $$r$$ from the axis, in the region $$r > a$$