Explanation
Correct answer: A.
Choice A is the best answer. This choice uses a transition that indicates a shift back in time. Since the first sentence talks about Thaden’s race win in 1929 and the second shifts back to talking about her record in 1928, this makes the most sense here.
Why the other choices are wrong
Choice B
Choice B is incorrect. This choice uses a disagreement transition. But this sentence actually agrees with and expands on the previous sentence by describing the earlier record that Thaden had "already" held.
Choice C
Choice C is incorrect. This choice uses a transition that indicates a shift forward in time, which doesn’t make sense here. A record in 1928 didn’t come after Thaden’s race win in 1929.
Choice D
Choice D is incorrect. This choice uses a cause-and-effect transition, which doesn’t make sense in this context—an event in 1929 can’t cause something in 1928.