Read the paragraph. Until 1965, half-dollars and quarters were 90% silver. In late 1965, the U. S. Mint ceased to produce silver coins and instead began to mint
"Sandwich coins made of copper and nickel. This minting was done to allow the silver to be used for industrial purposes, where it was badly
needed. Within a year, over 3.5 billion new coins had been minted, and the older silver ones were beginning to disappear from circulation.
Which sentence best summarizes the paragraph?