Tornado Alley Inc. estimated the following activity cost pools and activity measures for the upcoming year. What is the activity rate for the product design activity? Activity Cost Pool Activity Measure Customer relations $120,000 60 customers Product design $140,000 40 designs Organization-sustaining $60,000 N/A A. $2,000 per unit of activity B. $3,500 per unit of activity C. $2,600 per unit of activity D. $3,200 per unit of activity