A、The significance of "punctuality. " B、The change of the value of time in history. C、The history of industrialization. D、The de

W:(15)Watches and clocks seem as much a part of our life as breathing or eating. And yet, do you know the development of watches and clocks? Joseph, nice to meet you. Could you tell something about watches and clocks?
M: Jennifer, nice to meet you, too. Actually, watches and clocks were rare in the United States until the late 1850s.(12)In the late 1700s, people didn’t know the exact time unless they were near a clock. Those delightful clocks in the squares of European towns were built for the public.
W: After all, at that time, most citizens simply couldn’t afford a personal timepiece.
M: Well,(13)until the 1800s, in Europe and the United States, the main purpose of a watch, which, by the way, was often on a gold chain, was to show others how wealthy you were.
W: Um.. .well, talking about watch, we have to mention one word "wristwatch" that makes us realize the significance of "on time."
M: The word "wristwatch" didn’t even enter the English language until nearly 1900. By then, the rapid pace of industrialization in the United States meant that measuring time had become essential.(14)And since industrialization made possible the manufacture of large quantities of goods, watches became fairly inexpensive.
W: Yes, efficiency was now measured by how fast the job was done. Being "on time" had entered the language and life of every citizen.
M: Um, recently I often think that those who have left watch are likely to lose the sensitivity to time.
12. Where did people know the exact time in the late 1700s?
13. Why did the Europeans wear watches in the 1800s?
14. What factor makes wristwatch more affordable to the citizens?
15. What do the speakers mainly discuss?