@ITTutoring

Though, (going into way more detail than is required/helpful) wouldn't the common law precedents involve precedents in case law?

There are two uses of precedent which is confusing. The first refers to a lack of precedent in relation to how courts in Belize view indigenous rights. The second refers to the precedent (established practice) of Belize looking to other common law countries for "advice" when considering their own judicial decisions. Answer choice D refers to this second precedent.

The first is a problem in the passage which needs a solution. The second is what the Maya's want to happen in this case, since it would mean Belize would look to other common-law countries (Aus, Can, U.S) which have a judicial precedent of recognising indigenous peoples rights. The Maya want this.

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Also, the full answer to D is: "The courts of Belize have relied in analogous situations upon the sorts of common-law precedents that the Maya argue should be applied". The bit you cut out is paramount. It hasn't happened yet in this case—it's happened in the past and the Maya want it to happen again here (as the precedents in other common-law countries work in their favour).