Which of the following statements concerning the lab is TRUE?
(a) To avoid a huge imbalance, the difference between the masses of m1 and m2 should not exceed 10g.
(b) To get m3 to slide, m1 must be increased, never decreased.
(c) If m3 slides a couple centimeters and then stops again, you can count that as "just beginning" to slide.
(d) The dirtier the aluminum surface is, the better the experiment will be since dirty surfaces have more friction.

Lab experiments require attentiveness. If there is one thing missed or not taken seriously whole experiment could go wrong. In this case to slide m3 there should be more weight at m1. If the weight of m1 is lesser than m3 then the object will not slide. It will remain at the point where there is more weight. To slide an object there must be less frictional surface and more weight placed at the desired end point.