Answer:
C. Estimate costs.
Explanation: High-low method of accounting is a managerial accounting system designed to separate the fixed costs from the variable costs from a limited amount of data.
The "least-square" method of regression analysis is a analytical method used in accounting, Statistical and mathematical calculations to determine the "line of best fit" in a given set of data, it also makes visual representation of the Relationship existing between data which are analysed.