Two liquids of densities ρ1 and ρ2 (ρ2 = 2ρ1) are filled up behind a square wall of side 10 m as shown in figure. Each liquid has a height of 5 m. The ratio of the forces due to these liquids exerted on upper part MN to that at the lower part NO is (Assume that the liquids are not mixing)

(1) 1/4
(2) 2/3
(3) 1/3
(4) 1/2