请阅读短文，完成此题。
Seventy years ago, more than 160,000 Allied troops stormed the beaches of Normandy during the D-Day invasion. And while we all know that day served as a huge turning point for the Allied cause you probably haven't thought much about what those ,soldiers carried with them to eat during and after the invasion. Food had to be lightweight, nutritious and very high in energy; after all, these men were about to invade Nazi-occupied land. As it happened, the one substance that could fulfill all those requirements was a very unlikely item--a Hershey's chocolate bar.
The Hershey chocolate company was approached back in 1937 about creating a specially designed bar just for U.S. Army emergency rations. According to Hershey's chief chemist SamHinkle, the U.S. government had just four requests about their new chocolate bars: they had tow eight 4 ounces, be high in energy, withstand high temperatures and "taste a little better than a
boiled potato". The final product was called the "D ration bar", a blend of chocolate, sugar, cocoa butter, skim milk powder and oat flour. The viscous mixture proved too thick to move through the normal chocolate bar manufacturing set up at the Hershey plant, so initially each bar had to be packed into its 4-ounce mold by hand.
As for taste, well, most who tried it said they would rather had eaten the boiled potato. The combination of fat and oat flour made the chocolate bar a dense brick, and the sugar did little to mask the overwhelmingly bitter taste to the dark chocolate. Since it was designed to withstand high temperatures, the bar was nearly impossible to bite into. Most men who ate it had to shave slices off with a knife before they could chew it. And despite the U.S. Army's best efforts to stop the men from doing so, some of the D ration bars ended up in the trash. Later in the war, Hershey introduced a new version, known as the Tropical bar, specially designed for extreme temperatures of the Pacific Th
A.How Chocolate Was Made for the War
B.How Chocolate Helped Win the War
C.What Were the Requirements about Chocolate for the War
D.What Were the Differences between D Ration Bars and K Ration Packs