The diagram illustrates the Boltzmann distribution for the same gas at two different temperatures, $T_1$ and $T_2$. What quantity is shown on the y-axis, and which curve corresponds to the higher temperature?
- A$\text{number of molecules; } T_1$
- B$\text{number of molecules; } T_2$
- C$\text{molecular energy; } T_1$
- D$\text{molecular energy; } T_2$