What is social contract theory?

Which type of market produces the highest level of output at the lowest price to consumers?

Whether or not a given study has the possibility of causing harm to participants:

Atherapist at a free university clinic treats elementary school children with behavior problems who are referred by a social service agency. she is also a doctoral candidate who proposes using data she has and will collect about the children for a case-based research project. describe the type of parental permission which is required in this case?