What correctly describes water at 0 c and 1 ATM?

At 0 degrees Celsius and 1 atmosphere of pressure, water exists in a state of equilibrium between its solid form (ice) and its liquid form (water). This temperature is the freezing point of water, meaning that at this specific temperature and pressure, ice can coexist with liquid water. Below this temperature, water will freeze into ice, while above it, ice will melt into liquid water.