Answer:
Part A: The appropriate design would be: 300 male patients chosen should be suffering from ruptured disks in the lumbar region of the back, with similar magnitude of pain (or segregating these 300 as per magnitude of pain)
Part B: If the study consisted of 150 male and 150 female patients instead of 300 malepatients, I would change the study design, because the pain level could endure for femalecould vary compare to male.
Part C:Yes, I could design a double-blind, because it is a very good ways to show theeffect of the therapy because neither the participants nor the researchers knows whichgroups of participants is assigned to which treatment, and who are the groups of participant receiving it.