Which of the following is NOT mentioned in paragraph 1 as early means of transport?

Thông tin: Humans have always been searching for quicker and easier ways to get around. About 10,000 years ago, we built canoes made from logs of wood, while on land we started riding horses around 4.000 BC. Roughly 500 years later, we invented the wheel, which led to carts and wagons, and at almost the same time, the Egyptians invented the sailing boat.

Vậy nội dung không được đề cập là D. trains