Anegative test charge experiences a force to the right as a result of an electric field. which is the best conclusion to draw
based on this description?
the electric field points to the left because the force on a negative charge is opposite to the direction of the field.
the electric field points to the right because the force on a negative charge is in the same direction as the field.
no conclusion can be drawn because the sign of the charge creating the field is unknown.
no conclusion can be drawn because the amount of charge on the test charge is unknown.

The best conclusion based on the description is: The electric field points to the left because the force on a negative charge is opposite to the direction of the field.

Explanation:

As we know, that the electric force that has been exerted on a charge by an electric field is given as:        

                                         F =q×E

Where,

         F = Force

         q = Charge

         E = Electric field

We, can see a negative charge, with q having a negative sign, hence, we can say that the force F as well as the electric field E have the opposite depicting opposite direction. Because, the direction of the lines of an electric field shows that the direction of the electric force experiences positive charge in that particular electric field. Hence, in opposite direction negative charge will be experienced.