Flammable solvents, gases, and combustible materials may be ignited by which type of laser beam?

The correct choice highlights the properties of Class 4 lasers, which are high-powered lasers capable of producing significant heat and energy levels. Class 4 lasers are not only capable of causing eye and skin damage, but they can also ignite flammable solvents, gases, and combustible materials due to their intensity. This makes them particularly hazardous in environments where such materials are present.

In contrast, Class 1 lasers are considered safe under all conditions of normal use, as they do not emit enough power to cause any combustion or fire. Class 2 lasers can produce visible light but are limited in power, typically not enough to ignite materials. Class 3 lasers, while they have higher power levels, usually do not reach the thresholds necessary to ignite flammable materials in the same way that Class 4 lasers can. Thus, understanding the classifications of lasers and their capabilities is crucial for evaluating safety in environments where flammable substances are present.