20. Which of the following is NOT described in the passage as having been invented at Edison's first major laboratory in Menlo Park, New Jersey?
Your Answer is
Correct Answer is F
Explanation
According to the capital Menlo Park of the title stem, locate lines 19-25. The inventions here include improved telephones, phonographs, and electric lights. Item GHJ matches the positioning information, and does not mention the camera of item F.