(a) What is an unbounded linear optimization problem? How do we find if a given linear optimization problem has unbounded optimal solution? Give a real world example of a linear optimization problem where unbounded optimal solution may occur. Answer in at least six sentences. (b) Explain how the simulation process is used in business analytics models. What are the advantages of using simulation? What are its limitations? How can a simulation model be verified? Give a real world example where using simulation is appropriate. Use at least 8 sentences to answer this question. (c) What is an investment problem in linear optimization applications? Discuss the objective function and constraint requirements in an investment problem. Give a real world example of an investment problem. Use at least 8 sentences to answer this question. (d) Describe the concept and process of spreadsheet modeling and analysis. Give a real world example where spreadsheet modeling and analysis is useful. Answer in at least eight sentences.