Water Coming Out of Volcanic Sea Vents at the Bottom

Water coming out of volcanic sea vents at the bottom of the ocean can reach temperatures in excess of 300°C without boiling. How is this possible?

A) The heat is immediately transferred to the surrounding, very cold water.
B) The heat is immediately transferred to the surrounding volcanic rock.
C) The water and water vapor reach equilibrium under the extreme pressure of the ocean.
D) The extreme pressure exerted by the miles of ocean water above prevent the formation of any bubbles of water vapor.