Researchers working in Western Australia have discovered the oldest fragments of the Earth's early crust that have ye...

on February 29, 2020

Hello @DavidW,

You are asking the right question when you test this answer choice. What if microdiamonds formed that were not part of the Earth's crust? Would this contradict anything in the passage? No. A microdiamond could have naturally formed yesterday in my backyard, and it wouldn't contradict the given premises. They are talking specifically about microdiamonds that formed 4.2 billion years ago as a part of the Earth's crust. Their research is based on these particles. It doesn't matter if microdiamonds have occured in another time and place. So E does not have to be true.

On a must be true question, remember that we accept everything in the stimulus as truth. We are not going to doubt that the microdiamonds in question were part of the Earth's crust, because it says so in the first sentence.

A is correct because it matches our timeline.
Earth forms - - 300 million years - - - crust diamonds are formed

We know for certain that the crust began to form at most 300 years after the Earth's formation.

David on March 1, 2020

Ah, I didn't realize that we should accept everything in the stimulus as truth, so therefore those microdiamonds were part of the crust. Thank you very much!

Andrea on March 17, 2020

@DavidW Glad it makes more sense! Feel free to let us know if you have anymore questions.