Whose explanation greatly enhanced the general acceptance of Planck's energy quantization?

1. A second physicist made the idea persuasive. 2. Planck proposed that energy is quantized. 3. The general acceptance of Planck's energy quantization was greatly enhanced. 4. That came through Einstein's explanation of the photoelectric effect. _Source: OpenStax College Physics for AP Courses 2e (CC BY 4.0), Ch 29 'Quantum Physics', sections 29.1-29.8_