Which of the following is NOT the purpose of America’s central bank?

America’s Central Bank is part of a larger financial system called the United States Federal Reserve System. It is not a single bank, but a banking system with operations that are both public and private. Its purpose is to control the flow of money in the economy, to supervise banking activity and to protect the financial system.

About 10 percent of Europe’s present-day population seems to be resistant to HIV — a significantly higher proportion than on other continents. Researchers have traced this immunity to a genetic mutation that seems to have appeared some 2,500 years ago, and that protects white blood cells against penetration by HIV. From the mid-14th century through the 17th century the prevalence of the mutation increased, in tandem with repeated outbreaks of the plague. The researchers suggest that the mutation protected against the disease, which culled the population of people who lacked it.