Honastly no one knows but i would guess about 100
Your answer is B., because it is unidentifiable, so if they don't know the source, then why cite it right? :P :D So anyways, that's why your answer is B. =)
I hope I helped! =D
1: Reading because it helps you remember the key subjects as in nouns adjectives and more. Also because when you see a more complicated word you can always look around the word to see what it means and use it in your studies!
2. To concentrate on what your English teacher is saying so you will get better grades.
Answer:
is there a picture to go with these?