A mistake, if f is less than the static friction between object A and the ground, then there is definitely no force between A and B, that is, pressure!

B wrong! Similarly, if F is greater than the static friction between object A and the ground, there must be a force between A and B, that is, pressure! It should be said that not necessarily!

C correct! If B wants to move to the right, the resultant force must be zero, that is, A has a thrust equal to the sliding friction between B and the ground, that is, pressure!

D correct! If B wants to move to the right and accelerate evenly, the resultant force will inevitably move to the right, that is, A has a thrust on B that is greater than the sliding friction between B and the ground, that is, pressure!