43.According to the article, the Mayan society was very advanced in ________.
(A) the farming system
(B) mathematics
(C) sailing
(D) changing the climate

The first Americans probably came from Asia to North America 25,000 years ago or more. Over time they developed ways of farming and societies with different languages and cultures. About the time of the Roman Empire, there was a culture of the Mayas in Central America. Mayan society was known to be very advanced with their own system of mathematics and one of the best calendars in the world. They had a system of writing that was like ancient Chinese characters. Around the ninth century the population of the Mayans dropped. No one knows whether there was a problem of a change in the climate, war with other groups, or the wearing out of the soil. It was more than a thousand years later that Columbus discovered America. When he saw land after the trip across the Atlantic Ocean, he thought he was in India. (請依據上述文章，回答 41~45 題)