A Long Straight Wire Carries a Constant Current I $\mu$ ₀/4 $\pi$

A long straight wire carries a constant current I. The magnitude of the magnetic flux through the illustrated rectangular loop of wire is

A) ( $\mu$ ₀/4 $\pi$ ) 2Il ln(b/a)
B) ( $\mu$ ₀/4 $\pi$ ) 4Il ln(b/a)
C) ( $\mu$ ₀/4 $\pi$ ) Il ln[(a + b) /(b - a) ]
D) ( $\mu$ ₀/4 $\pi$ ) 4Il ln[(b - a) /(b + a) ]
E) ( $\mu$ ₀/4 $\pi$ ) 2Il ln[(b - a) /(b + a) ]