题目解析:
assistance: 帮助。和选项C呼应。对应原文About a year after the opening of the first Kinetoscope parlor in 1894, showmen such as Louis and Auguste Lumiere, Thomas Armat and Charles Francis Jenkins, and Orville and Woodville Latham (with the assistance of Edison's former assistant, William Dickson) perfected projection devices.这句话中说了这些人完善了投影仪器,在爱迪生助手的assistance下,从语境中也不难猜出是帮助的意思。所以正确答案是C