What scientists might've able to learn about the seawater that existed Millions of years ago by studying rocks that came into contact with sea water at

For their research, the team analysed a piece of rock melt, called komatiite -- named after the type occurrence in the Komati river near Barberton in Mpumalanga -- that are the leftovers from the hottest magma ever produced in the first quarter of Earth's existence (the Archaean). While most of the komatiites were obscured by later alteration and exposure to the atmosphere, small droplets of the molten rock were preserved in a mineral called olivine. This allowed the team to study a perfectly preserved piece of ancient lava.

Explanation:

We examined a piece of melt that was 10 microns (0.01mm) in diameter, and analysed its chemical indicators such as H2O content, chlorine and deuterium/hydrogen ratio, and found that Earth's recycling process started about 600 million years earlier than originally thought," says Wilson. "We found that seawater was transported deep into the mantle and then re-emerged through volcanic plumes from the core-mantle boundary."

The research allows insight into the first stages of plate tectonics and the start of stable continental crust.

What is exciting is that this discovery comes at the 50th anniversary of the discovery of komatiites in the Barberton Mountain Land by Wits Professors, the brothers Morris and Richard Viljoen," says Wilson.

b is the correct answer