The correct answer is: A. Hot objects to cold objects.
Heat is a form of energy that is transferred from a hotter object to a colder object. This transfer of energy can occur in a number of ways, including conduction, convection, and radiation.
Conduction is the transfer of heat through direct contact between two objects. For example, when you touch a hot stove, the heat from the stove is transferred to your hand through conduction.
Convection is the transfer of heat through the movement of fluids. For example, when you boil water, the heat from the stove is transferred to the water through convection. The hot water rises to the top of the pot, while the cold water sinks to the bottom. This creates a current that circulates the water and distributes the heat evenly.
Radiation is the transfer of heat through electromagnetic waves. For example, the sun radiates heat to the Earth through electromagnetic waves.
In all of these cases, heat is transferred from a hotter object to a colder object. This is because heat always flows from a region of higher temperature to a region of lower temperature.
Options B, C, D, and E are incorrect because they do not describe the correct direction of heat flow.