Entropy is defined as the amount of disorder within a system. Thus, systems that are disorganized have greater entropy. Likewise, systems that have more organization have lower entropy. Assuming that the room prior to the party was organized, this would be the option that has the lowest entropy.
The Second Law of Thermodynamics states that all closed systems gravitate towards a maximization of entropy. Energy must be applied to a system to overcome this natural tendency towards entropy.
Entropy can be related to each state of matter. Because the particles of solids are found in an organized manner with little movement, it can be said that solids have the lowest entropy out of the tree states of matter. Likewise, because gas particles move the most and fastest, it can be said that gases have the greatest entropy out of the three states of matter.