Step 1: Understanding the equation.
The equation \( \frac{pV}{kT} \) relates pressure \( p \), volume \( V \), temperature \( T \), and the Boltzmann constant \( k \). It is a part of the ideal gas law in terms of molecules. The ideal gas law in molecular form is:
\[
pV = NkT
\]
Where \( N \) is the number of molecules. Therefore, \( \frac{pV}{kT} \) gives the number of molecules of gas in the given volume.
Step 2: Conclusion.
Thus, \( \frac{pV}{kT} \) represents the number of molecules of gas in one mole. The correct answer is (D) number of molecules of gas in one mole.