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. an analysis of aggregate data comparing statewide high school graduation rates provided by the state department of public instruction, using county tax information. a feasibility study for implementing a year-round school program, focusing on economic issues such a facilities utilization and transportation costs.

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.

Explanation:

Whenever a researcher intends to do research with human beings, he or she must comply with federal regulations of the country where the research will be conducted so that their research is valid and the welfare and safety of the humans involved are guaranteed. Following this line of reasoning, among the options given in the question, the one that represents an obedience to the definition of research with human beings is:

"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."