The attractions that allow molecules of krypton to exist in the solid phase are due to London dispersion forces.

Here's why:

* Krypton is a noble gas. Noble gases are monoatomic, meaning they exist as single atoms rather than molecules.

* London dispersion forces are the weakest type of intermolecular force. They arise from temporary fluctuations in electron distribution around an atom, creating temporary dipoles. These temporary dipoles induce dipoles in neighboring atoms, leading to a weak attraction.

* While krypton is a very small atom, the London dispersion forces are still significant enough to hold krypton atoms together in the solid state at low temperatures. The larger the atom, the more electrons it has, and the greater the potential for temporary dipoles, making London dispersion forces stronger.

Important Note: While hydrogen bonding and dipole-dipole interactions are stronger intermolecular forces, they don't play a role in krypton because it's a nonpolar atom.