Stiffness is measured as Modulus of elasticity

Stiffness is a property that describes the resistance of an object to deformation when a force is applied to it. It is a measure of how much an object resists being stretched, compressed, or bent. The stiffness of a material is determined by its modulus of elasticity.

Modulus of elasticity:
The modulus of elasticity, also known as Young's modulus, is a measure of the stiffness of a material. It quantifies the relationship between stress (force per unit area) and strain (deformation) in a material under elastic deformation. It is denoted by the symbol E and has units of pressure (Pascal or Pa).

The modulus of elasticity is defined as the ratio of stress to strain within the elastic limit of a material. It represents the slope of the stress-strain curve in the linear elastic region. The higher the modulus of elasticity, the stiffer the material.

Other options:
a) Modulus of plasticity: The modulus of plasticity is a measure of the ability of a material to undergo plastic deformation. It is not directly related to stiffness.

c) Resilience: Resilience is the ability of a material to absorb energy without permanent deformation. It is related to the area under the stress-strain curve up to the elastic limit. It is not a direct measure of stiffness.

d) None of these: The correct answer is option 'B' - Modulus of elasticity.

In conclusion, stiffness is measured as the modulus of elasticity. It is a property that describes the resistance of an object to deformation when a force is applied. The higher the modulus of elasticity, the stiffer the material.