The diagram below shows two substances, A and B, which are at different temperatures.

What will happen when substance A is dropped into substance B?

a
Substance A and B will eventually reach the same temperature.
b
Substance A and B will exchange heat, and they both will reach 50°C.
c
Substance A and B will exchange heat, and they both will reach 25°C.
d
Substance A will get even warmer as heat flows into it from substance B.