| When performing a vibration analysis for rotating machinery, what is essential? |
| A) A baseline vibration signature should be established as a reference, but no historical record of periodic analyses need be maintained. Vibration amplitudes at various frequencies are compared. |
| B) A baseline vibration signature should be established as a reference, and a historical record of periodic analyses should be maintained. Vibration amplitudes at various frequencies are compared. |
| C) A historical record of periodic analyses should be maintained, but no baseline vibration signature need be established as a reference. Vibration amplitudes at various frequencies are compared. |
| D) A baseline vibration signature should be established as a reference, and a historical record of periodic analyses should be maintained. Vibration amplitudes are compared with no need to examine frequencies. |
