Which of These Describes the Best Experimental Design to Test

Multiple Choice

Which of these describes the best experimental design to test the idea that scrotal temperature is less with boxers than with briefs?

A) Take an equal number of men wearing boxers and men wearing briefs and have them go into a clinic and have their scrotal temperatures measured.
B) Recruit a number of men of approximately the same age and have some put on boxers and some put on briefs and then measure their scrotal temperatures.
C) Recruit a number of men of approximately the same age with half wearing boxers and half wearing briefs.Have them spend time in a room of the same constant temperature and then measure their scrotal temperatures.
D) Take the first 100 men who come into a fertility clinic,record who are wearing boxers and who are wearing briefs,and then measure their scrotal temperatures.