State the conclusion based on the results of the test. The mean of the pressure required to open a certain valve is known to be mu equals 8.3 psi. Due to changes in the manufacturing process, the quality-control manager feels that the average pressure has been reduced. The null hypothesis was rejected. Question content area bottom Part 1 Choose the correct answer below. A. The mean of the pressure has been reduced. B. There is sufficient evidence that the mean of the pressure required to open a certain valve has been reduced. C. There is sufficient evidence that the mean of the pressure required to open a certain valve has not changed. D. There is not sufficient evidence that the mean of the pressure required to open a certain valve has not changed. E. The mean of the pressure has not changed. F. There is not sufficient evidence that the mean of the pressure required to open a certain valve has been reduced