We can see here that using the phase diagram for CO₂, carbon dioxide at 20°C and 25 atm pressure: C. It is in the gas phase.
A phase diagram is a graphical representation that shows the equilibrium conditions between different states of matter (solid, liquid, gas) of a substance as a function of pressure and temperature, or sometimes as a function of pressure and volume.
From the provided phase diagram for carbon dioxide (CO₂):
At 20°C temperature and 25 atm pressure, the point falls within the region that represents the gas phase of CO₂.
Therefore, the phase of carbon dioxide at 20°C and 25 atm pressure is a gas.