Economic-The U.S. money supply is currently backed by ???thank you?

Question

The U.S. money supply is currently backed by

gold or silver.

fractional reserves.

the commodity in which it is denominated.

nothing.

the U.S. Treasury.

Answer 1

d) nothing.

Just trust and nothing more, funny, isn't it?

Answer 2

Nothing I think.  We were based on a gold standard but put a stop to that in mid 1970s (or early).  Yeah..about 30 years ago with Richard Nixon.  I think its not based on anything (currency).