What should the student do in her investigation to produce these results?
A. She should place a negatively charged rod near the left sphere.
B. She should place a positively charged rod near the left sphere.
C. She should place two negatively charged rods near each sphere.
D. She should place two positively charged rods near each sphere.
The correct answer would be A. She should place a negatively charged rod near the left sphere.
By placing a negatively charged rod near the left sphere, it will induce a positive charge in the left sphere through the process of electrostatic induction. This will cause an attraction between the positively charged left sphere and the negatively charged right sphere, resulting in a movement of the spheres towards each other.