Information is provided to you showing results for the past two periods. Analyse the results and select the correct answer. Select one: a. As costs are changing together with changes in sales, then these must all be variable costs. b. As the costs are changing from one period to the next, then these must all be variable costs. c. In period 1 and 2 the fixed costs are $2300 and the variable costs in period 2 is $800 d. In period 2 the fixed costs are $700 and the variable costs are $2400