Which of the Following Is an Example of a Researchable

Which of the following is an example of a researchable topic?

A) Should homeschoolers include their children in cooperative schools for high school level courses?
B) Are homeschooled students happier than are students in traditional schools?
C) Should homeschooled students be included in our district's prom planning committee?
D) Are there differences in achievement test scores between those homeschooled for part of the day or not at all in our district?