Heat can never flow from
a. hot to cold
b. cold to hot
c. liquid to solid
d. solid to liquid

The correct sentence is:
Heat can never flow from b. cold to hot.

In fact, heat always flows from hot to cold objects. The reason is the following: in an object with higher temperature, the particles move/vibrate faster than the particles in an object with lower temperature. When the two objects are in contact, therefore, the particles of the hotter object have more energy than the particles of the colder object, so the particles of the hotter object transfer more energy to the particles of the colder object, on average. As a result, heat always flows from hot objects to cold objects.

Which principle states: "geologic processes taking place on earth today operated similarly in the past and can be used to explain past geologic events"? a. lateral continuity