Four charges Q₁, Q₂, Q₃ and Q₄ of same magnitude are fixed along the x axis at x = $$-$$2a, $$-$$a, +a and +2a, respectively. A positive charge q is placed on the positive y axis at a distance b > 0. Four options of the signs of these charges are given in List I. The direction of the forces on the charge q is given in List II. Match List I with List II and select the correct answer using the code given below the lists.

List I		List II
P.	Q$$_1$$, Q$$_2$$, Q$$_3$$, Q$$_4$$ all positive	1.	+x
Q.	Q$$_1$$, Q$$_2$$ positive; Q$$_3$$, Q$$_4$$ negative	2.	$$ - $$x
R.	Q$$_1$$, Q$$_4$$ positive; Q$$_2$$, Q$$_3$$ negative	3.	+y
S.	Q$$_1$$, Q$$_3$$ positive; Q$$_2$$, Q$$_4$$ negative	4.	$$ - $$y

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