Water exists as a liquid at room temperature primarily due to the presence of strong hydrogen bonds between adjacent water molecules.

Hydrogen bonds are a strong type of intermolecular force (force between molecules) that cause water molecules to attract each other and resist separation into a gas phase at typical room temperatures.

A. electrovalent bond (ionic bond) is a strong force that exists between ions, like in table salt (NaCl), not within or between water molecules. Water is a polar covalent compound.

B. covalent bond is the strong intramolecular force that holds the hydrogen and oxygen atoms together within a single water molecule (\(\text{H}_{2}\text{O}\)). The existence of the molecule itself depends on the covalent bonds, but the liquid state (how molecules interact with each other) is due to the intermolecular hydrogen bonds.

C. van der waals forces are weaker intermolecular forces present in all molecules. While present, they are much weaker than hydrogen bonds. If only van der Waals forces were present, water would be a gas at room temperature, similar to other hydrides like hydrogen sulfide (\(\text{H}_{2}\text{S}\)).