Diffraction greatest for longest wavelength Steps:

• Use λ = v/f to find wavelengths, v = 340 m/s, d = 0.80 m.
• A: λ = 340/240 = 1.42 m (> d).
• B: λ = 340/800 = 0.425 m (< d).
• C: λ = 340/2700 ≈ 0.126 m (<< d).
• D: λ = 340/4300 ≈ 0.079 m (<< d).
• Compare θ ≈ λ/d; largest θ for largest λ means most diffraction.

Why A is correct:

• Longest λ gives largest θ ≈ λ/d per single-slit diffraction formula, maximum bending and spreading.

Why the others are wrong:

• B: Shorter λ yields smaller θ, less spreading than A.
• C: Much shorter λ, minimal diffraction, more straight propagation.
• D: Shortest λ, smallest θ, least diffraction overall.

Final answer: A