What environmental factors affect epoxy resins?

The selection of humidity and temperature as the answer is accurate because these two factors significantly influence the curing process and overall performance of epoxy resins. Humidity can impact the resin's ability to cure properly; high humidity levels can lead to moisture absorption, which may interfere with the hardening process and affect the mechanical properties of the final product.

Temperature also plays a vital role in determining the rate of curing and the viscosity of the resin. Higher temperatures generally accelerate the curing process, while lower temperatures can slow it down, potentially leading to incomplete curing. Both of these factors are crucial for achieving the desired properties in epoxy resins, including strength, durability, and adhesion.

Other options like light and air, moisture and light, or pressure and altitude do impact materials in various ways, but their effects on epoxy resins are not as profound as those posed by humidity and temperature. Light can cause degradation in some materials, while moisture has more direct consequences when coupled with humidity in relation to curing processes. Pressure and altitude might affect the physical conditions under which epoxies are used, but typically do not influence the curing and performance characteristics as significantly as humidity and temperature.