The owner of a bookstore in a college town notices that demand for certain textbooks peak during certain times of the year. She assumes that these peaks coincide with the beginning of semesters when professors recommend these books to the students. She decides to estimate future sales of these textbooks by measuring the interconnection between sales and announcement of courses that recommend them. Which of the following methods of sales forecasting is she using? A) Jury of executive opinion method
B) Dependence method
C) Time-series analysis
D) Correlation analysis