Eight wires cut the page perpendicularly at the points shown. Each wire carries current i. Odd currents are out of the page and even currents into the page. The line integral `int vecB. vec dl`-along the loop is

Explanation

According to ampere.s, circuital law
`intovecB.vec(dl)=mu_(0)i_("enclosed")`
`intovecB.vec(dl)=mu_(0)[i_(8)-i_(5)+i_(2)+i_(4)]`
since, all the wires carry same current of `i_(0)`, we have
`intovecB.vec(dl)=2mu_(0)i_(0)`