Câu hỏi:

Mark the letter A, B, or D to indicate the correct option that best fits each of the blanks.

The concept of time zones was invented to solve a pressing issue (18) ________ in the 19th century. (19) ________, each city operated on its own local time, usually set according to the position of the sun. This was practical for local scheduling but created chaos for scheduling trains (20) ________.

The man credited with the invention of time zones is Sir Sandford Fleming. A Canadian engineer, Fleming proposed a worldwide system of time zones in 1879 after missing a train in Ireland because its printed schedule listed a PM time as an AM. His proposal divided the world into twenty-four hour-long segments, (21) ________.

Initially, Fleming’s idea was met with resistance. (22) ________ as rail and telegraph networks expanded. The International Meridian Conference, held in Washington D.C. in 1884, adopted his system. As a result, the world's major countries agreed to use a single meridian, running through the Royal Observatory in Greenwich, England, (23) ________.

Today, time zones are an essential part of our global society, facilitating everything from travel to international business. Fleming’s contribution remains a prime example of practical problem-solving which leads to a revolutionary change in how the world operates.

As a result, the world's major countries agreed to use a single meridian, running through the Royal Observatory in Greenwich, England, (23) ________.