There is an electric field at a certain point P, where initially there is no charge. A point-like object is placed at point P, and a force on the object is observed. Next the object is removed and another point-like object is placed at the same point. There is a force on this object that is different than the one observed for the first object. The following can be concluded:

A)The two forces must be in the same direction.
B) One of the objects has a positive charge, the other one has a negative charge
C) The two objects have the same charge but different mass.
D) The two objects must have different charges.
E) This is umpossible; the force should be the same for both objects because the electric field at the point hasn't changed

D) The two objects must have different charges.

To determine the correct conclusion, we need to apply the principles of electric field and the interaction between charges.

When an electric field is present at a point, it indicates the presence of electric forces on any charged object placed at that point. In this scenario, we observe that two different objects experience different forces when placed at the same point.

Now let's analyze the options one by one:

A) The two forces must be in the same direction.
This conclusion cannot be drawn based on the given information. The two forces can be in the same direction, opposite directions, or even perpendicular to each other.

B) One of the objects has a positive charge, the other one has a negative charge.
This conclusion cannot be determined solely based on the observed forces. The forces could be explained by various charge combinations involving positive and negative charges.

C) The two objects have the same charge but different mass.
This conclusion cannot be determined based solely on the forces observed. The forces experienced by objects depend on both the charges and masses involved.

D) The two objects must have different charges.
This conclusion is a possibility. The observed forces could be due to the different charges on the objects. However, more information is needed to validate this conclusion.

E) This is impossible; the force should be the same for both objects because the electric field at the point hasn't changed.
This conclusion is incorrect. The force experienced by an object depends not only on the electric field but also on the properties of the object, such as its charge or mass. Even if the electric field at the point remains the same, different forces can be observed due to different objects interacting with that electric field.

In conclusion, based on the given information, the most plausible conclusion is D) The two objects must have different charges. However, further experimentation or information is needed to confirm this conclusion.