You are asked to compare the cost of four different antibacterial medicines. Which of the following treatment courses is the lowest cost? a) Medicine A costs £17.00 for 28 tablets. The adult dose is one tablet twice a day and the usual treatment duration is 7 days. b) Medicine B costs £30.00 for 100 tablets. The adult dose is one tablet four times a day and the usual treatment duration is 7 days. c) Medicine C costs £20.00 for 25 tablets. The adult dose is one tablet twice a day and the usual treatment duration is 5 days. d) Medicine D costs £25.00 for 14 tablets. The adult dose is one tablet each day and the usual treatment duration is 5 days.