Two rods of the same weight and equal length have different thickness

Two rods of the same weight and equal length
have different thickness. They are held vertically on the surface of sand as shown in figure. Which one of them will sink more?
image
Why?
Answer:
Rod B will go deeper as it has a smaller area of contact, therefore the same force (weight of the rod) produces more pressure. In case of rod A the same force produces less pressure.