Limit of Proportionality Ends Linear Stress-Strain Region

Steps:

• Examine the stress-strain graph for an elastic solid, which shows load versus extension or stress versus strain.
• Identify the initial linear portion where Hooke's law applies (stress ∝ strain).
• Locate the point where the graph deviates from this straight line, marking the limit.
• Confirm this as the boundary before non-proportional behavior begins.

Why B is correct:

• B marks the end of the linear region where stress is directly proportional to strain, as defined by Hooke's law (σ = Eε).

Why the others are wrong:

• A: Represents the origin, start of the proportional region, not its limit.
• C: Lies in the curved region, indicating plastic deformation beyond proportionality.
• D: Indicates the fracture or breaking point, far past the proportional limit.

Final answer: B