While plotting a control chart, it is noted that two of the last three points are greater than 2 sigma, four out of the last five points are beyond 1 sigma, and eight successive points are on one side of the center line. This information suggests that one should:

Select one:

a. notify supervisor know of a discrepancy

b. Investigate to determine what has changed

c. Stop the process immediately

d. Take more readings and continue to plot