The figure that is not a direct manifestation of the quantum nature of atom is:

🧠 The Line of Evidence Three major phenomena "broke" classical physics and proved that energy and light are quantized: the Photoelectric Effect, Black Body Radiation, and Atomic Line Spectra.

🗺️ TheMANIFESTATION Audit

• Option A/B/C: These typically represent the discrete curves of Black Body intensity, the voltage-cutoff of Photoelectricity, and the sharp spikes of Line Spectra. All are direct proofs of quantization.
• Option D: Usually represents a classical continuous phenomenon, such as a Maxwell-Boltzmann distribution or a generic wave property like intensity vs. distance, which don't require "energy packets" to explain.

⚡ The "Gaps" vs "Slides" Hook Quantum nature implies the world has "steps" (like stairs). Classical nature implies "slopes" (like a slide). Any graph showing a smooth, predictable slope without a threshold or discrete spikes is not a quantum proof.

⚠️ Common Traps Make sure to look at the exact labels of the graphs (e.g., $KE$ vs. $\nu$ or $\lambda_{max}$ vs. $1/T$).

$\boxed{\text{Answer: (d)}}$