Hello, I have no idea how to solve this question. It's about Nash-Bertrand equilibrium. Could you please explain the correct answer for me? Thank you so much ^^

The annual market demand for cheese is a constant 5,500 kilograms (kg) per year, regardless of the price charged. Assume that cheese is a completely undifferentiated and homogenous product. There are four potential suppliers to the cheese market with cost structures and capacities indicated below. What market price, per kilogram (kg) of cheese, arises in Nash-Bertrand equilibrium? Unit Cost Capacity Company ($/kg) (kg./year) The Big Cheese Inc. 5.00 3,000 Lactose Intolerant Inc. 9.00 1,500 Wallace & Gromit Cheese Co. 7.50 1,000 Who Cut The Cheese Co. 6.00 2,500 O Just under 5.00 O Just under 6.00 O Just under 7.50 O Just under 9.00 O Above 9.00