If the S&P 500 Falls by 20 Percent, the NYSE

If the S&P 500 falls by 20 percent, the NYSE will:

A) do nothing if the drop occurs after 2:30 P.M.
B) halt trading for one hour.
C) halt trading for one hour if the decline occurs before 3 P.M.
D) halt trading for one-half hour if the decline occurs after noon.
E) cease trading for the day.