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Diamonds, the hardest mineral known to humankind, are made of pure carbon. A diamond is formed when the carbon, buried deep underground, is compressed by the weight of the earth above it. The black mineral turns into a crystal. The word diamond comes from the Greek word that means "unbeatable."
According to many ancient beliefs, wearing a diamond makes a person unbeatable in way. The great military leader, Napoleon had a famous stone, called the Regent diamond, set into his sword.
What detail in the passage helps explain the origin of diamonds?
a. The Regent diamond helped Napoleon win battles.
b. Diamonds have the power to make the wearer strong.
c. Diamonds are crystals formed from carbon.
d. Diamonds are mined in Greece.
What is "Diamonds are crystals formed from carbon"?