Final answer:
RF stacked A-scans (option B) are the most common type of display used for setting and calibrating Time-of-Flight Diffraction (TOFD) inspections due to their ability to enhance signal-to-noise ratios and assist in calibration.
Step-by-step explanation:
The type of display most commonly used to set and calibrate Time-of-Flight Diffraction (TOFD) inspections is B) RF stacked A-scans. TOFD is an ultrasonic testing (UT) technique used primarily for the detection of flaws in welds. The RF (Radio Frequency) stacked A-scan allows the operator to view the amplitude of the received ultrasonic signal as a function of time, which is crucial for accurately setting up the TOFD inspection parameters.
The A-scan provides the raw signal, while RF stacking enhances signal-to-noise ratio, which supported by multiple A-scans shown on top of each other, helps in calibrating the TOFD system. Options A, C, and D represent other types of UT display methods, but they are not as commonly used for TOFD calibration as RF stacked A-scans are.