NASA Wanted to Know If Extended Periods of Weightlessness Would

Multiple Choice

NASA wanted to know if extended periods of weightlessness would have an impact on long-term circulatory function.The agency located seven former astronauts who had spent more than one month in space under conditions of weightlessness,and tested all aspects of their cardiovascular function.What sort of research did NASA conduct in this situation

A)  experimental research 
B)  survey research 
C)  case study research 
D)  naturalistic observation