Consider the following statements.
A. Heat flows from an object in liquid state to an object in solid state;
B. Heat flows from an object with higher thermal energy to one with lower thermal energy;
C. Heat flows from an object at higher temperature to an object at lower temperature.

Which statements are true?
1. All are true.
2. C only
3. A and B only
4. A only
5. B and C only
6. None is true.
7. B only
8. A and C only