2 Points
Which of the following ideas provided an important step toward a more
complete understanding of blackbody radiation?

Following ideas provided an important step toward a more  complete understanding of blackbody radiation is given below

Explanation:

Planck wanted to understand black body radiation. The black body may be modeled by a box, with a small hole.We heat the box up, wait for the system to reach a stationary state (at a fixed temperature), and see what kind of electromagnetic radiation (intensity as a function of frequency) comes out of the hole. In , Rayleigh and Jeans3 tried to apply classical mechanics to this problem, and they calculated correctly that the black body would emit the electromagnetic radiation with a distribution of frequencies. However, the larger the frequency, the larger its intensity - an absurd conclusion, what is known as an ultraviolet catastrophe.All materials emit light. A tungsten metal wire can illuminate a room with black body radiation at 2800 K. Black body radiation is a combination of spontaneous and stimulated emission from an array of thermally excited oscillators. Planck‘s radiation law describing this phenomenon is considered to be the foundation for modern physics and quantum theory. While no material behaves exactly as a black body, all emit light by this mechanism. External energy in the form of heat enters the materials system, and light is emitted to maintain a steady-state, constant temperature.