Which one of the following best summarizes the main idea of the passage? A. Seventeenth-century scientific experimentation would have been impossible without the work of paid laboratory technicians. B. Seventeenth-century social conventions prohibited upper-class laboratory workers from taking public credit for their work. C. Seventeenth-century views of scientific discovery combined with social class distinctions to ensure that laboratory technicians' scientific work was never publicly acknowledged. D. Seventeenth-century scientists were far more dependent on their laboratory technicians than are scientists today, yet far less willing to acknowledge technicians' scientific contributions. E. Seventeenth-century scientists liberated themselves from the stigma attached to manual labor by relying heavily on the work of laboratory technicians.