5. Which of the following were reasons that China closed their doors to the rest of the world? (Mark all that are true) Japanese pirates were attacking Chinese ships
Fighting the Mongols in the North was too expensive.
Confucian values taught not to pursue anything abroad.
Sending a fleet of ships to collect tributes from territories

According to the federal regulations, which of the following studies meets the definition of research with human subjects? a study of twenty 4th grade classrooms in which researchers ask the schools to systematically vary the time of day reading is taught, and collect weekly assessments of reading comprehension for each child over a three-month period.the collection of data, by a playground designer hired by the superintendent of schools, about the physical dimensions of school playgrounds, presence of fencing, and the kinds of equipment currently provided.a feasibility study for implementing a year-round school program, focusing on economic issues such a facilities utilization and transportation costs.an analysis of aggregate data comparing statewide high school graduation rates provided by the state department of public instruction, using county tax information.