One Disadvantage of Program Trading Is That

One disadvantage of program trading is that

A) during a market crash, computers tend to automatically execute huge numbers of buy orders as prices fall. This accelerates and strengthens the market decline.
B) investors program their computers to buy or sell particular stocks when the stock hits a particular price.
C) during a market crash, computers tend to automatically execute huge numbers of sell orders as prices rise. This accelerates and strengthens the market decline.
D) during a market crash, computers tend to automatically execute huge numbers of sell orders as prices fall. This accelerates and deepens the market decline.