Maybe if we look simlpy by the electron withdrawing nature of the biphenyl substittuent as a whole in the (3,4,5) ring, then the meta position i.e. 4 should come out to the preferable answer
@YusufHasan Nice.. minor nitpick though, the structure on wikipedia is a network solid and it isn't individual molecules.. These mechanism do not work for such molecules right? chemistry.stackexchange.com/questions/136.466/… Andselisk's comment
@Safdar No these network solid things are for the solid form, the reactions mostly happen in the aqueous or gaseous form...there these dimer formations are common
For solid network reactions at low temperatures these mechanisms might not work ofcourse