When heat is added to a liquid at the boiling temperature, it converts the liquid into a gas at the same temperature because a) the heat added is lost by the system. b) the heat added is absorbed by the container. c) the heat added is used to break the bonds between the gas molecules. d) the heat added is used to break the bonds between the liquid molecules.

The answer to this is D.

In internal energy of a substance, it's the sum of toatl kinetic energy of the molecules and the total potential energy. Kinetic energy is just the speed of the molecules, so it's the temperature. But since this situation does not have a temperature change, so the heat added is added up in the potential energy. Potential energy increases when the substance changes state. It is the energy where used to break up the bonds of the liquid, since the molecules are closer in liquid than gas.
This heat is called latent heat.
Therefore, whenever a substances changes its state but not the temperature when heated, the heat applied (of course some is lost to surroundings) is used in the breaking of bonds.