Final answer:
The statement that B. closer temperatures make it harder to transfer heat from hot to cold is true, as heat flow relies on a temperature difference as the driving force.
Step-by-step explanation:
The statement that is true regarding heat flow between two objects at different temperatures is B. The closer the two temperatures are the harder it is to move heat from hot to cold. This is because heat transfer occurs due to a temperature difference between two objects. As the temperatures of the objects get closer, the driving force for heat transfer, which is the temperature difference, decreases, and thus it becomes more difficult to transfer heat.
Heat spontaneously flows from an object at a higher temperature to another at a lower temperature, corresponding to the loss of thermal energy by the hotter object and a gain by the cooler. The overall direction of heat transfer is always from the hotter to the colder object until thermal equilibrium is reached. When the temperatures are equal, there is no net heat transfer.