Potassium chlorate decomposes in which temperature range?

Why this is the correct range
Potassium chlorate ($KClO_3$) is a strong oxidizing agent that undergoes thermal decomposition when heated. Its behavior is highly temperature-dependent: Melting Point: It melts at approximately 629 K (356°C).Decomposition Range: Significant decomposition begins shortly after melting. Between 673 K and 878 K (400°C to 605°C), it breaks down into potassium chloride and oxygen gas. The chemical equation for this thermal decomposition is:$$2KClO_3 \x right arrow{\Delta} 2KCl + 3O_2 \up arrow $$The Role of a CatalystIn laboratory settings (like the common school experiment to produce oxygen), a catalyst called Manganese Dioxide ($MnO_2$) is added.  Effect: It lowers the decomposition temperature significantly, allowing the reaction to occur at much lower temperatures (around 473 K to 603 K).Crucial Note: Without the catalyst, you must reach the higher range specified in Option D for the reaction to proceed efficiently.