The center line (p-bar) for a p-chart is 0.50 with an ULC = 0.70 and a LCL = 0.35. The results of the next eight sample means are 0.45, 0.60, 0.39, 0.44, 0.48, 0.58, 0.54, and 0.64. Which of the following actions should be taken in this scenario? a. Nothing—the process is in control. b. Investigate assignable causes because there is a bad trend (run). c. Investigate assignable causes because four observations are above the center line. d. Investigate assignable causes because four of the eight samples are below the center line.