An analyst has gathered the following expenditure information for three different firms, each of which has a sales level of $4 million. Costs for firms under consideration (in millions) Firm A Firm B Variable Costs $2.00 $2.60 Fixed Costs $1.00 $1.30 Interest Expense $0.20 $0.00 Which firm has the highest degree of operating leverage (DOL)? Firm C $2.40 $1.40 $0.20