the expression below was formed by combining different gas laws. $vpropto\frac{nt}{p}$ which law was used to…

Brief Explanations:

Avogadro's law states that at constant temperature and pressure, the volume of a gas is directly proportional to the number of moles of the gas. In the given expression $V\propto\frac{nT}{P}$, when $T$ and $P$ are held constant, $V\propto n$, which is in line with Avogadro's law. Boyle's law relates volume and pressure ($PV = k$), Charles's law relates volume and temperature ($\frac{V}{T}=k$), and Gay - Lussac's law relates pressure and temperature ($\frac{P}{T}=k$).

Answer:

C. Avogadro's law