What does the term stress refer to when applied to metal?

When discussing metals and the concept of stress, it is defined as the internal resistance offered by the material to deformation when subjected to an external force. This internal force arises from the material's structure as it responds to loading. Stress is quantified as the force applied per unit area within the material, and this is a key concept in materials science and mechanical engineering.

Understanding stress is essential when assessing how materials behave under different conditions of load, which can influence strength, durability, and failure modes. The other options provided might relate to different aspects of material science, such as external forces, temperature changes, or elasticity, but they do not capture the specific definition of stress as it pertains to internal forces generated in response to external loading.