ISOLATING and OBSCURING were hotly debated answers on a vocabulary in context question that appeared on both the US and International October 3, 2026 SATs.
Unfortunately, I do not have enough information to make a confirmed statement about the correct answer. Here is what I do know:
The passage was about the fossilization of dinosaur bones.
DIMINISHING and HAPHAZARDOUS were wrong answers.
ISOLATION describes the process of separating or detaching something
OBSCURING refers to making something unclear and therefore difficult to understand.
I believe there is a very good chance that OBSCURING is the correct answer. Here’s why: During fossilization, iron and other minerals in the surrounding environment naturally seep into bone tissue over millions of years. Because iron is already incorporated into the fossilization process, finding iron doesn’t automatically prove the original T. Rex biological material was preserved inside it. The background mineral iron OBSCURES or hides/masks whether the iron came from the dinosaur’s blood/tissue or from the surrounding soil.
In short, I believe OBSCURING is the most logical answer because the passage implied that the soil the fossil was buried in also had iron. This OBSCURED or made it unclear how much iron was originally in the fossil.
OBSCURING – to make something unclear
ISOLATING – to detach or separate something