In 2015, a team led by materials scientists Anirudha Sumant and Diana Berman succeeded in reducing the coefficient of friction (COF) between two surfaces to the lowest possible level--superlubricity. A nearly frictionless (and, as its name suggests, extremely slippery) state, ________

Which choice completes the text so that it conforms to the conventions of Standard English?

Question

Accepted Answer

superlubricity is reached when two surfaces' COF drops below 0.01.

Answer

when their COF drops below 0.01, two surfaces reach superlubricity.

Answer

two surfaces, when their COF drops below 0.01, reach superlubricity.

Answer

reaching superlubricity occurs when two surfaces' COF drops below 0.01.