JEE Main 2023 Physics question

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

• (A)inversely proportional to r in the region r < a and uniform throughout in the region r > a
• (B)directly proportional to r in the region r < a and inversely proportional to r in the region r > aCorrect
• (C)zero in the region r < a and inversely proportional to r in the region r > a
• (D)uniform in the region r < a and inversely proportional to distance r from the axis, in the region r > a