Please help! Will mark brainlist if correct

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.

In the years after world war ii, which of the following caused many people from asian and african countries to migrate to europe? a. the end of the soviet union b. new economic opportunities after colonialism ended c. the religious freedom found in europe d. new laws allowing greater numbers of immigrants into european countries

What name is given to the money that had to be paid by germany in ww2