Limit of Proportionality Ends Linear Elastic Region

Steps:

• Identify the stress-strain graph for an elastic solid, showing initial linear increase in stress with strain.
• Recall Hooke's law: stress is directly proportional to strain up to the proportionality limit.
• Locate the point where the graph deviates from the straight line, ending proportionality.
• Select the option marking this deviation point.

Why B is correct:

• B marks the end of the straight-line portion, where stress ∝ strain per Hooke's law, beyond which proportionality fails.

Why the others are wrong:

• A: Represents the origin or early linear phase, not the limit.
• C: Indicates the yield point, starting plastic deformation after proportionality.
• D: Shows the breaking or ultimate failure point, far beyond elastic limits.

Final answer: B