The following cost data is for a perfectly competitive seller: If product price is $45, the rm will: O shut down. 0 produce 4 units and realize a $120 economic prot. O produce 5 units and realize a $15 economic prot. 0 produce 6 units and realize a $100 economic prot. An Industry has ten firms with market shares as follows; 15%, 15%, 15%, 15%, 8%, 8%, 8%, 6%, 6%, 4%. Calculate the four-firm concentration ratio. O 60% O 15% 53% O 1104 O 54% O 100%