Which below best describes how surfaces shall be prepared for Ultrasonic examination :-

The finished contact surfaces shall be free from weld splatter and any roughness that would interfere with free movement of the search unit or impair the transmission of ultrasonic vibrations;

The weld surfaces shall be finished so they cannot mask or be confused with reflections from defects, and should merge smoothly into the surfaces of the adjacent base materials;

The volume of base material through which the sound will travel in angle beam examination shall be completely scanned with a straight beam search unit to detect reflectors which might affect interpretation of angle beam results

all of the above.