Final answer:
Tensile strength is the ability of a material, particularly metals, to resist being pulled apart under tensile stress. It is an essential material property in structural and material engineering. The correct option for what tensile strength refers to is 'c. The ability of a metal to resist being pulled apart'.
Step-by-step explanation:
Tensile strength refers to the maximum stress that a material can withstand while being stretched or pulled before breaking. In essence, it is the ability of a material, such as metal, to resist being pulled apart. It is a critical measure of a material's performance, especially in structural applications where tension forces are prevalent. When a material is under tensile stress, forces act on it in a way that attempts to elongate the material, which is measured as tensile strain. This concept is vital in understanding how different materials will behave under various loads and can be crucial in engineering and design to prevent material failure.
To specifically answer the student's question, option c. 'The ability of a metal to resist being pulled apart' defines tensile strength accurately. The other options refer to different kinds of strength or stress responses, such as shear strength (to withstand a twisting force) or compressive strength (to resist being crushed). It's important to understand these different strengths when selecting materials for various engineering applications.