Which property in atension test is an indication of stiffness of the material?

The property in a tension test that indicates the stiffness of the material is the modulus of elasticity, also known as Young's modulus. It is defined as the ratio of stress (force per unit area) to strain (deformation per unit length) within the elastic limit of the material. A higher modulus of elasticity indicates a stiffer material, while a lower value indicates greater flexibility. This property is crucial for understanding how materials will behave under tensile loads.