According to https://en.wikipedia.org/wiki/Young's_modulus, it is the slope of the elastic portion (the linear part at the start) of the curve. That makes B correct.songoku said:
Young's Modulus, also known as the elastic modulus, is a measure of the stiffness of a material. It is defined as the ratio of stress (force per unit area) to strain (proportional deformation) in a material in the linear elasticity regime of a uniaxial deformation.
Among commonly known materials, diamond has the greatest Young's Modulus. Diamond's Young's Modulus is approximately 1,200 GPa (Gigapascals).
Diamond has a high Young's Modulus due to its strong covalent bonding between carbon atoms in a tetrahedral structure. This rigid bonding network makes diamond extremely stiff and resistant to deformation.
Yes, carbon nanotubes and graphene are synthetic materials known for their exceptionally high Young's Modulus, which can be even higher than that of diamond. Graphene, for example, has a Young's Modulus of about 1,000 GPa.
Young's Modulus is typically measured using tensile testing. A sample of the material is subjected to a controlled tensile force, and the resulting elongation is measured. The Young's Modulus is then calculated using the stress-strain relationship in the linear elastic region of the material's deformation.