The correct answer is circled. Unsure how to get the answer though. Can someone please explain? Thanks!

9. Below is information about the units produced and manufacturing costs for Snow Enterprises for the past six mor Number of units produced Total manufacturing costs Month January February 7.940 7,500 6,400 6,600 $5,900 $5,460 $5,000 S5,500 $5,100 $5,840 March April 4,740 May June 7,800 Using the high-low method, what is the monthly fixed manufacturing cost? A. $ 800 $11,000 3,915 D. $ 1,985