Question: Many years ago, purple dye was made from some sea animals. Then, in 1856, William Perkins tried to make a new medicine. Instead, he found a way to make purple dye from coal. What is a positive effect of his discovery?

  Options: 
 A. Some diseases can be treated.
 B. Purple clothing can be made.
 C. Sea animals are not needed to make purple dye.
 D. Perkins is famous for discovering a new medicine.
Answer: C