Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions. 

      George Washington Carver showed that plant life was more than just food for animals and humans. Carver's first step was to analyze plant parts to find out what they were made of. He then combined these simpler isolated substances with other substances to create new products. 

      The branch of chemistry that studies and finds ways to use raw materials from farm products to make industrial products is called chemurgy. Carver was one of the first and greatest chemurgists of all time. Today the science of chemurgy is better known as the science of synthetics. Each day people depend on and use synthetic materials made from raw materials. All his life Carver battled against the disposal of waste materials and wamed of the growing need to develop substitutes for the natural substances being used up by humans. 

      Carver never cared about getting credit for the new products he created. He never tried to patent his discoveries or get wealthy from them. He turned down many offers to leave Tuskegee Institute to become a rich scientist in private industry. Thomas Edison, inventor of the electric light, offered him a laboratory in Detroit to carry out food research. When the United States government made him a collaborator in the Mycology and Plant Disease Survey of the Department of Agriculture, he accepted the position with the understanding that he wouldn't have to leave Tuskegee. As an authority on plant diseases - especially of the fungus variety - Carver sent hundreds of specimens to the United States Department of Agriculture. At the peak of his career, Carver's fame and influence were known on every continent.

With what topic is the passage mainly concerned?

• A. 
  The work and career of George Washington Carver
• B. 
  The research conducted at Tuskegee Institute
• C. 
  The progress of the science of synthetics
• D. 
  The use of plants as a source of nutrition