Money is often said to be socially defined what does this mean

Money is often said to be "socially defined." What does this mean? a. That a nation's money supply must be backed by something socially acceptable such as gold. O b. That only the Bank of Canada can supply money and this bank is owned by the public. O c. That parliament has defined what money is. O d. That the money supply includes all public and private securities purchased by society. Ore. That society defines what money is in terms of what it deems acceptable