In this set of material, the reading passage suggests three main purposes of the making of carved stone balls. However, the lecturer finds all of this idea dubious and skeptical and unlikely to happen and refutes them all.
First of all, the reading passage claims that carved stone balls were used as weapons in hunting or fighting because some of them have holes and grooves on their surfaces. On the contrary, the professor refutes this idea by explaining that if the balls were used as weapon, there would be cracked and had signs of damage. But the the surfaces of balls were very well preserved. Hence, this idea cannot be a logical solution.
Furthermore, the reading passage posses that the carved stone balls might be used as a part of primitive system of weights and measures as they all have the same size. Conversely, the professor opposites this idea by explaining that the balls were have the same size, but made from different materials with different densities. So, they may have the same size, however, their weights were completely different. Therefore, this idea cannot solve the problem.
Finally, it was mentioned in the reading passage that one of the promising proposes of the carved stone balls that they were served a social purposes as in contrast to a practical or utiliarian one, as the balls were have elaborated designs and they might marked the important social status of their owners. In contrast, the professor refutes this point by saying that carved stone balls were very simple and it was improbable to be the marked sights of famous people. In addition, it is known that the regarded people were buried with their objects. But none of the balls were found in the graves with the bodies. Thus, this idea will not assist the real purpose.