A parallel sentence mentions the same grammatical expression twice. I would go with "D". 'Passed' and 'Demonstrated' are both past tense words that express the same past tense grammatical idea.
If you have more questions, feel free to ask me.
Introduced is a regular verb because all you did was add -ed at the end. Good luck!
Usually if information is used from other sources, it cited in the back of the book. They would cite what info was taken and used. You could always check there to see if it's accurate. Usually it's labeled as "Works Cited".
Hoped this helps!!
~Bob Ross™
My mother has a great admiration and belief in my father. (try this)
