14. According to the passage, which of the following was the final innovation that allowed letters to be sent without postmaster scrutiny?
Your Answer is
Correct Answer is F
Explanation
Stem requirements: Which of the following inventions is the latest to prevent letters from being monitored by the post office?
L42-69 is based on finding the age of each invention, the latest is the use of street drop boxes in item F in the United States
Item F: L61-63, street drop boxes: 1858 .
Item G: L58-60, registered mail: 1856.
Item H: L51-54, sealed envelopes: 1849.
Item J: L44, postage stamps: 1840.