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?

Answer and Explanation

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.