Which of the following is a type of developer used in penetrant inspection?

In penetrant inspection, the correct type of developer is aqueous particulate. This method, often used for non-destructive testing, involves applying a developer to the penetrant that has been absorbed into any surface-breaking defects of a material. The aqueous particulate developer helps to draw the penetrant out of the defects to make them visible under ultraviolet or white light.

Aqueous particulate developers are beneficial because they are water-based, making them easier to clean and more environmentally friendly compared to solvent-based options. They facilitate the visibility of penetrants by providing a contrasting background for fluorescent materials, which enhances the detection of even minor flaws in the inspected parts.

The other options do not fit the criteria for developers used in penetrant inspection. Liquid emulsifiable developers, for example, are a form of developer but not an aqueous one. Powdered solvent refers to a form of solvent product used for cleaning rather than developing. Magnetic particulate is used for magnetic particle testing, which is a completely different type of non-destructive testing technique focused on detecting surface and near-surface defects in ferromagnetic materials.