Why A over B

@Meredith, The correct answer to the main point question (a) must be true and (b) must describe the main point. The issue with (B) is that it is unsupported by the passage. Only one of the court decisions (1991) challenged the notion that the custom must be regular and continuous to count as traditional, whereas the prior decision (1986?) upheld the FWS regulations (lines 35-38). Let me know if you have any other questions.

I can see why part of the answer A is correct, but I'm confused as to whether the passage is discussing the term "tradition" in the US legal system or purely Alaskan law? Please help and thanks in advance!