1) The first reason is the decline in family size and the increase in single-adult households. 2) In more traditional societies, families tended to be large. 3) it made economic sense for one person to devote her/himself to time-consuming domestic tasks such as growing and preparing food. 4) Nowadays, people tend to live in ever smaller family units. 5) If each family were to spend large amounts of time growing and processing food, this would be a poor use fo society's human resources.下面关于这个段落阐述说法正确的选项有哪些？