<p>i don't understand how the answer is wire 1.</p>
<p>using the right hand rule for the wire with current I, the magnetic field goes in below the wire and out above the wire. using the right hand rule for the wire with current 2I, the magnetic field goes in above the wire and out below the wire. at point 1, the magnetic fields cancel out (I is going in, 2I is going out)</p>