Magnetic particle inspection is primarily used to detect which of the following?

Magnetic particle inspection is a nondestructive testing technique specifically designed to identify surface and near-surface discontinuities in ferromagnetic materials. This method involves magnetizing the material and applying ferrous particles to the surface. When there are defects such as cracks, inclusions, or laps, these particles will congregate around the flaws, forming visible indications that can be easily detected under adequate lighting conditions.

This technique is particularly adept at detecting flaws that are directly on the surface or just below it, making it an essential tool in ensuring the integrity of components in various industries, especially aerospace and manufacturing, where surface integrity is critical. While it can effectively highlight certain issues that may extend slightly beneath the surface, it is not designed to reveal deep internal flaws, which would require more advanced techniques such as ultrasonic or radiographic testing. Therefore, the focus of magnetic particle inspection is firmly on surface and near-surface defects, validating the correctness of that answer.