Marge, the cost analyst of Better Light Solutions, has been asked to analyze transportation costs for purchases. Marge plans to determine the cost function for total transportation costs and believes that variable costs can be predicted based on the number of purchase orders. Which of the following best describes what must be done before the cost function can be estimated?? Question 6 options: A correlation must be established between number of purchase orders and variable costs of transportation. The objective function has to be determined. A cause-and-effect relationship must be established for the number of purchase orders and variable costs of transportation. Time-series or cross-sectional data must be collected before a cause-and-effect relationship is established