Observation of the four previous months has identified the following total cost data for production costs within Danny Dog plc. Activity level Total cost 10,000 28,000 5,000 21,000 60,000 98,000 30,000 56,000 Based on the hi-lo method of cost estimation, what is the variable cost per unit of production? a. 2.00 b. 1.70 C. 2.50 d. 1.40