Stress-strain curves reflect Young's modulus as slope in elastic region

Steps:

• Young's modulus Y equals stress/strain, so slope of stress-strain curve is Y.
• Brass has lower Y than steel, so its curve has smaller slope.
• Both wires follow linear Hooke's law initially from origin.
• Graph B shows steel line steeper than brass, matching lower Y for brass.

Why B is correct:

• Slope of stress-strain curve is Y (from σ = Yε), so brass curve has lower slope than steel.

Why the others are wrong:

• A: Both curves have same slope, ignoring Y difference.
• C: Brass curve steeper, contradicting lower Y for brass.
• D: Nonlinear curves from start, but elastic region is linear.

Final answer: B