Concept:This sentence uses the parallel structure "the + comparative adjective, the + comparative adjective" to show that two things change together.Explanation:The first clause is "The earlier we leave", where "earlier" is a comparative adjective.The second clause must also begin with "the" followed by a comparative adjective."Better" is the comparative form of "good", so "the better for us" correctly completes the pattern."The best" is a superlative, "the much better" is not the correct comparative form, and "it is better" does not fit the parallel structure.Answer:C. the better