Two thin, long parallel wires separated by a distance ‘d’ carry a current of ‘i’ A in the same direction. They will

(1) attract each other with a force of μ0I²/(2πd)
(2) repel each other with a force of μ0I² / (2πd)
(3) attract each other with a force of μ0I²(2πd²)
(4) repel each other with a force of μ0I²/(2πd²)