∴ They are equal in volume;

When an object is placed on a level ground,

∴F=2G=2mg=2ρVg，

∴ The ratio of brick pressure to horizontal ground in the four methods is FA: FB: FC: FD = ρ A: ρ B: ρ C: ρ D =1:2: 3: 4.

As can be seen from the figure, A: B: C: D = 4: 8: 4: 8 =1:2:1:2.

∫P = FS，

∴ A: B: C: D = 1: 1: 3: 2, so option A is correct and option B is incorrect;

(2) The pressure of brick in methods A, B and C is FA ′: FB ′: FC ′ = GA ′: GB ′: GC ′ = ρ A: ρ B: ρ C =1:2: 3.

As can be seen from the figure, the stress area ratio at this time is S A': S B': S C' = 4: 4: 2 = 2: 2: 1,

Therefore, the pressure ratio of bricks in methods A, B and C is 1: 2: 6, so the CD option is incorrect.

So choose a.