Main idea/ main point/ purpose questions all require us to identify the main point/ argument the author is trying to make. Ask yourself, what is this passage about? What is the author trying to tell us?
With this in mind, let's look at the answer choices:
(A) Prior to an appellate ruling in Carrier vs. Bell...
Incorrect. This is neither the main idea nor is consistent with the information in the passage. The passage cites this case to illustrate the doctrine of abandonment is inapplicable to certain objects, but it does not mean that NA did have legal grounds to demand the return of artifacts prior to this ruling.
(B) Property law offers...
Incorrect. Again this is neither the main idea nor is consistent with the passage. Property law is cited as just one of the example of how common law can provide a basis for NA claims, nowhere does it says that it offers the MOST promising remedies.
(C) The older the grave...
Incorrect. This statement is consistent with the information in the passage (lines 18-21) but it is not the main idea. The author uses most of the passage to discuss how common law - and property law as an example - can be used to establish a basis for claims once standing is established, hence this detail is only relevant to the first paragraph but is not the main point of the passage as a whole.
(D) In cases in which NA can establish standing..
Correct. Per the above, the author contends that common law can be used as a basis for NA claims and illustrates and develops this contention in subsequent paragraphs.
(E) NA are unlikely to make significant progress...
Incorrect. This statement is out of scope and is unsupported by the passage.
Let me know if this helps and if you have any other questions.
