a) Explain how the "shape" of utility function on wealth, that is U(w), affects the risk attitude of an individual. Please explain the intuition behind. (6 points) b) Focused on what we have discussed in lectures, explain how English auction would be the most common auction format adopted by sellers in practice. (4 points) c) Based on what we have discussed in lectures on the models related to adverse selection with two types, including (i) insurance model (high-risk type vs low-risk type) and (ii) Principle-Agent Model on the adverse selection of labor (high-cost type vs low-cost type): We can see that to solve the adverse selection problem, a type will be "hurt". Explain intuitively the economic logic behind which type will be "hurt". "The requirement of this part is not to name which type to be hurt in the model (i) and (ii). but the economic logic for a particular type to be hurt. (4 points)