Read the following statement and identify the major weakness in the researcher's claim, if any.
a.Researchers assigned participants with depression to an experimental drug treatment finding that 70% of the participants exhibited fewer depression symptoms, concluding that the experimental drug was highly effective in reducing depression symptoms.
b.No random selection.
c.Correlation does not imply causation.
d. No major weaknesses.
e.Lack of a control condition.
f.Case study evidence.