Each description in Column I hints at whether the defect sits inside the part or on its surface, and whether the check is a one-time inspection or continuous monitoring. Match that hint to the method that fits it best, then check the four options.
(A) P-1, Q-4, R-2, S-3: an internal flaw in a thick wheel goes to Ultrasonic, continuous in-service crack tracking goes to Acoustic Emission, an internal inclusion goes to Radiography, and a surface crack goes to Dye Penetrant. Each method sits exactly where its strength lies. Correct.
(B) P-3, Q-2, R-4, S-1: sends the internal wheel flaw to Dye Penetrant, but dye penetrant only reaches surface defects and cannot see inside a solid wheel. Wrong.
(C) P-3, Q-2, R-1, S-4: again places the internal wheel flaw under Dye Penetrant and the in-service crack under Radiography, but radiography needs a still exposure and is not built for continuous monitoring. Wrong.
(D) P-1, Q-3, R-4, S-2: places the in-service crack under Dye Penetrant, which is a one-time surface check, not a continuous in-service technique. Wrong.
Only option (A) lines every description up with the method actually used for it.
Let's summarize:
Ultrasonic: internal flaws in thick, solid parts like a railroad wheel.
Acoustic Emission: continuous, in-service tracking of crack growth.
Radiography: internal inclusions, imaged with X-rays or gamma rays.
Dye Penetrant: surface-breaking cracks only, such as in an aluminum alloy.
So the correct match is P-1, Q-4, R-2, S-3, option (A).
