Which statement best describes adhesives?

Adhesives are designed primarily to bond materials together permanently or at least provide a strong, durable connection that can withstand various stresses and environmental conditions. This capability makes them essential in many engineering and construction applications, where a long-lasting bond is crucial for structural integrity and performance. By creating a robust bond between substrates, adhesives contribute to the overall strength of the assembly, allowing for greater design flexibility and material usage.

The other statements, while they may address certain aspects of adhesives, do not encapsulate their primary function as effectively. For example, while some adhesives can be removed, this is not a defining feature of most adhesives, particularly those intended for permanent applications. Additionally, while it is true that certain adhesives are designed for specific materials, many types are versatile and can bond a wide variety of substrates. Lastly, while adhesives may interact with surfaces and influence their properties to some extent, their primary function is not to alter material properties but to provide a strong bond. Thus, the statement that best captures the essence of what adhesives do is that they are used to bind materials together permanently.