I know the answer is NOT C

After the emergency ambulance service in question 6 had established its control chart, the following week, on the fifth day of Spring Break, the following sample of ambulance response times (in minutes) was collected: 4.8, 6.5, 7.9, 8.5. Based on these data, should the ambulance service be concerned about its performance? a. No, X-bar = 6.9, R-bar = 3.7; sample mean and range are in control limits; no corrective action is needed. b. Yes, X-bar =6.9,R-bar =3.7; sample mean and range are outside control limits; corrective action is needed. c. Yes, X-bar = 6.9, R-bar = 3.7; sample mean is within control limit, sample range is outside control limit; corrective action is needed. d. Yes, X-bar = 6.9, R-bar = 3.7; sample mean is on control limit and last two response times are outside of control limits; corrective action should be taken. e. None of the above