The force analysis of a small object shows that the object is subjected to gravity, supporting force and friction force downward along the inclined plane, so the supporting force of the object is FN=mgcosθ and the friction force is f=μFN. When the tension increases, only the upward tension along the inclined plane increases, while the supporting force and friction force of the object remain unchanged. Because the supporting force and friction between the object and the inclined plane are the relationship between acting force and reaction force, the objects on the inclined plane are opposite to each other. The direction of friction should be opposite to the direction of the horizontal component of tension; So the direction is to the left;

Therefore, choose: B.