Use the Following Information for Questions

Multiple Choice

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.
-What is the explanatory variable in the study?

A) The improvement in grip strength
B) The treatment group (either Yoga or control group)
C) The severity of carpal tunnel syndrome
D) The age of the patient.