Studies on a machine that molds plastic water pipe indicate that when it is injecting 27.01 mm diameter pipe, the process standard deviation is 0.56 mm. The pipe has a specification of 27.01 mm plus or minus 1.95 mm. What is the process capability index (Cp)?

a. 1.161

b. 0.5804

c. 2.321

d. 3.482