Final answer:
The point at which the electric force on a test charge is zero between two charges of +3 C and +9 C at a distance of 2 meters is closest to the +9 C charge.
Step-by-step explanation:
To find the point between the charges at which the electric force on a test charge is zero, we need to consider the balance between the attractive and repulsive forces. Let's use the principle that the forces between charges are inversely proportional to the square of the distance between them. If we assume the test charge is positive, then the closer it is to the +9 C charge, the stronger the repulsive force it experiences. On the other hand, the closer it is to the +3 C charge, the stronger the attractive force it experiences. Therefore, the point at which the electric force on the test charge is zero should be closer to the +9 C charge.
Based on the options provided, the point 0.5 meters from the +9 C charge (option A) would be the most likely answer.