Final answer:
The subject of this question is History. It relates to the study of calendars, irrigation, temples, and mummification in ancient civilizations.
Step-by-step explanation:
The subject of this question is History. The calendar, irrigation, temples, and mummification mentioned all relate to different aspects of ancient civilizations and their practices. In history, we study the development of various calendars and their significance in different cultures, including the 260-day and 365-day calendars used in Mesoamerican civilizations and the calendars used by Babylonians, Egyptians, and other ancient societies. We also learn about the importance of irrigation systems, the construction and purpose of temples in different civilizations, and the practice of mummification in ancient Egypt.