Use the Following Information for Questions

Use the following information for questions:
A study of 42 patients with carpal tunnel syndrome (symptoms of burning numbness in the wrist to difficulty making a fist) was done ("Yoga based intervention for carpal tunnel syndrome," Garfinkel et al, JAMA 1998; 280:1601-1603) . Subjects were randomly assigned to a yoga group or a control (where they were offered a wrist splint to supplement their current treatment) . Results showed that subjects in the yoga group had significant improvement in grip strength, while subjects in the control group did not.
-Can a conclusion that yoga caused the improvement in grip strength be made?

A) A cause and effect relation might be concluded because the study had a control group.
B) A cause and effect relation might be concluded because the study was a randomized experiment.
C) A cause and effect relation cannot be concluded because of the small sample size.
D) A cause and effect relation cannot be concluded because not all subjects in the control group accepted the splint.