In the Past, the Mean Running Time for a Certain $H _ { 0 } : \mu = 8.4$

In the past, the mean running time for a certain type of flashlight battery has been 8.4 hours.
The manufacturer has introduced a change in the production method and wants to perform a hypothesis test to determine whether the mean running time has increased as a result.The hypotheses are:
$H _ { 0 } : \mu = 8.4$ hours
$H _ { A } : \mu > 8.4$ hours
Explain the result of a Type II error.

A) The manufacturer will decide the mean battery life is greater than 8.4 hours when in fact it is greater than 8.4 hours.
B) The manufacturer will decide the mean battery life is less than 8.4 hours when in fact it is greater than 8.4 hours.
C) The manufacturer will decide the mean battery life is 8.4 hours when in fact it is 8.4 hours.
D) The manufacturer will decide the mean battery life is 8.4 hours when in fact it is greater than 8.4 hours.
E) The manufacturer will decide the mean battery life is greater than 8.4 hours when in fact it is 8.4 hours.