Non-conclusive and I believe the experiment to be flawed as the average probably depends more on the two options than on what people believe. It might be more interesting as a way to test for anchoring - or unanchoring through showing two different options. But in short, neither option did well but the two-choice option did better when responders had consistently missed the actual value (the telephone question) and so both of the two choices were more correct than what most people were giving.