Scenario: You are a clinical trial nurse involved in the study "The Effect of Selenicereus undatus (dragon fruit) extract in Lowering Blood Pressure of Hypertensive Patients" 23. Which of the following is the independent variable? Need Online Assistance?
A. The effect of Selenicereus undatus B. Lowering of blood pressure C. Administration of Selenicereus undatus D. None of the above