Final answer:
The triggers that cause accumulated smoke to ignite are high temperatures and the right mixture of fuel and oxygen. Heat is required for ignition and to sustain the fire, and when fuel reacts with oxygen in the air, combustion occurs.
Step-by-step explanation:
The student's question is about the triggers that may cause accumulated smoke to ignite. Based on the information provided regarding the necessary elements for a fire to occur—heat, fuel, and oxygen—the correct answer to the question would involve these elements. The combination of heat and fuel in the presence of oxygen creates the conditions necessary for combustion to take place. During combustion, a reactant combines with oxygen to produce heat and light in the form of a flame. For ignition, the right temperature and a proper mixture of fuel (combustible material) and oxidant (oxygen) are essential. The heat source is responsible for the initial ignition and continual burn, drying out nearby fuel and warming the surrounding air. Oxygen supports the chemical processes that take place during burning, and fuel serves as the combustible material that reacts with the oxygen.