• Assertion (A) is False: Rayleigh scattering occurs when particle diameter is much smaller than radiation wavelength ($d \ll \lambda$); its scattering intensity is inversely proportional to the fourth power of wavelength ($I \propto \lambda^{-4}$), NOT the third power.
• Reason (R) is True: Because scattering varies as $\lambda^{-4}$, shorter wavelengths (blue light, $\approx 0.4\ \mu\text{m}$) are scattered far more strongly than longer wavelengths (red light, $\approx 0.7\ \mu\text{m}$), explaining the blue color of the clear daytime sky.
• Conclusion: (A) is false but (R) is true (Option 4).

Correct option: (4) (A) is false but (R) is true.