In a Graph of the History of U

In a graph of the history of U.S. energy use since 1950, why does the graph drop sharply after 1973?

A) The Texas oil fields produced far less oil beginning in 1973, resulting in rationing and a switch to natural gas.
B) Analysts have not yet found a good explanation for this drop in U.S. energy use.
C) The 1973 mideast oil embargo was followed by increased prices and a drop in consumption.
D) The Texas oil fields produced far less oil beginning in 1973, causing a price increase and a drop in consumption.
E) The 1973 mideast oil embargo was followed by gasoline rationing and a switch to domestic natural gas.