The answer is D, the other ones are facts or scenarios meaning that they had to occur to be noticed.
Answer:
The Sumerian Calendar and the Sumerian system of irrigation were both connected by one thing; farming. Both these inventions made farming easier for the Sumerians.
Explanation:
Based on their observations, they invented a calendar which had 12 months and each month had around 30 days. The days of a month would start and end at sunset. Each day had 12 hours, 6 hours of daylight and 6 hours of night.
