<u>Answer:</u> The correct answers are a lake, the air in a room and the air outside.
<u>Explanation:</u>
There are 3 modes by which heat can be transferred:
1. Conduction: In this process, heat is transferred whenever there is a direct contact between the two objects.
2. Convection: In this process, the heat is transferred whenever there is a movement of fluid. Fluid can be a liquid or gas.
3. Radiation: In this process, the heat is transferred whenever there is direct transfer of energy through the space.
From the given options,
Heat flow due to convection can occur in a lake, the air in a room and the air outside because, in these hot air rises up after capturing heat energy and cold air being more dense settles down and the process of heating continues.
Hence, the correct answers are a lake, the air in a room and the air outside.