Does St John's Wort Have a Significant Effect in Treating Major

Does St. John's wort have a significant effect in treating major depression? A study looked at 340 adult outpatients suffering from major depression as measured by their HAM-D score, randomly assigning each subject to either a placebo, St. John's wort, or a second active treatment for comparison.
The St. John's wort study doesn't show that St. John's wort is equivalent to a placebo. If the researchers still believe in the effectiveness of St. John's wort in treating depression, how might they change their study?

A) They should carefully choose which patients get the placebo and which get St. John's wort to guarantee significant results.
B) They should increase the sample size.
C) They should decrease the sample size.
D) They shouldn't have a placebo group; they should give all the subjects the St. John's wort so they can measure its effect more precisely.