Why is C correct?

Could someone explain this question to me?

@Shiyi-Zhang, Happy to help. The paragraph that gives us information on the 'continuous change' hypothesis is the second paragraph, which goes from lines 12 to 25. In this paragraph, we're told that proponents of the 'continuous change' hypothesis don't think that federal law had A MARGINAL IMPACT on the economic progress made by black people in America between 1940 and 1975. Rather, proponents of this hypothesis argue that slowly evolving historical forces, like long-term trends in education that improved segregated schools for blacks, led to the earning potential of blacks increasing relative to the earning potential of those attending white schools. From this, we know that the proponents of the 'continuous change' hypothesis are basically saying the government didn't do anything to improve blacks' situations; rather, evolving historical forces did. The question asks us to choose the answer that best states the position of proponents of the 'continuous change' hypothesis regarding the relationship between law and racial discrimination. We know that the proponents didn't think the government really helped at all, so we're looking for an answer choice that says that the law/government had little or no impact. (C) says that legislation alone has had little effect on racially discriminatory behavior. This accurately states how the proponents feel about the government and law's role in reducing racially discriminatory behavior, so its' the correct answer choice. Does this make sense? Let us know if you have any more questions!