An Army Depot That Overhauls Ground Mobile Radar Systems Is $\mu _ { d } = 0$

An army depot that overhauls ground mobile radar systems is interested in improving its processes.One problem involves troubleshooting a particular component that has a high failure rate after it has been repaired and reinstalled in the system.The shop floor supervisor believes that having standard work procedures in place will reduce the time required for troubleshooting this component.Time (in minutes) required troubleshooting this component without and with the standard work procedure is recorded for a sample of 19 employees. assuming that we define our differences as Time without standard work procedure - Time with standard work procedure, the correct alternative hypothesis is

A) $\mu _ { d } = 0$ .
B) $\mu _ { d } < 0$ .
C) $\mu _ { d } > 0$ .
D) $\mu _ { d } \neq 0$ .
E) None of the above.