A School Nurse Decided to Begin a "Don't Smoke,don't Start

A school nurse decided to begin a "don't smoke,don't start" program.To determine whether the program has any effect,an experimental trial study was planned.Which of the following actions would the nurse take?

A) Divide the students into two groups (smokers and nonsmokers) ,teach the course to both groups,and then observe for changes in beliefs.
B) Divide the students into two randomly chosen groups,teach the program to all students,and then determine learning and smoking behaviors through a posttest.
C) Use two randomly chosen groups,teach the program to one group,and then determine differences in knowledge and smoking behaviors between the two groups.
D) Screen each student,and look for evidence of smoking behaviors.