For the same Fmax, if you increase the number of lines of resolution...

When you increase the number of lines of resolution while keeping the maximum frequency (Fmax) constant, you effectively enhance the ability of the measurement system to discern finer details in the frequency domain. However, this improvement comes at the cost of longer test time.

The relationship between lines of resolution and test time is directly tied to how the data is being acquired. More lines of resolution mean that the system needs to perform additional measurements at intermediary frequency intervals to capture the increased detail. Each line corresponds to a distinct frequency bin where data needs to be collected, so if there are more lines, more data points must be gathered, leading to a longer duration to complete the measurement.

This concept is essential in vibration analysis, where the accuracy and fidelity of data are critical for diagnosing issues. While increasing the number of lines may provide a more detailed picture of the vibration characteristics, it inherently requires more time to collect and process the data effectively. Thus, choice C is accurate in stating that the measurement will take longer to complete due to this increase in resolution lines.