Rearrange wave equation for linear plot Steps:

• Use v = f λ to substitute into v² = g λ / (2 π), yielding (f λ)² = g λ / (2 π).
• Simplify to f² λ = g / (2 π).
• Rearrange to f² = [g / (2 π)] × (1/λ).
• Plot f² (y-axis) against 1/λ (x-axis) for y = m x, a straight line through origin. Why D is correct:
• f² is directly proportional to 1/λ per the rearranged equation, with slope g/(2 π). Why the others are wrong:
• A: f ∝ 1/√λ, nonlinear curve.
• B: f ∝ 1/λ^{3/4}, nonlinear.
• C: f ∝ √(1/λ), nonlinear square-root relation.

Final answer: D