SAT II Chemistry Question?

In Choice 1, you have to consider the fact that entropy is a function of multiplicity - for this, you have to know Boltzmann's Law, which I learned in my Thermodynamics cl in college. The basic idea is that since a mixture of two or more components can have a different elemental structure (a small sample of a mixture can have unique ratios of each compound), and a pure compound has only one elemental structure (consisting of only its own molecules), the mixture has higher entropy than either of the two component gases