A PDF must be put into an external program after being exported to be edited, you can't make direct changes to it. This eliminates answer choice A.
You can print documents with other extensions besides .pdf, such as those of Word documents and such, it doesn't have to be a .pdf. This eliminates answer choice B.
Since you can't directly edit a PDF, C is a possible answer.
Files don't have to be saved as a .pdf, especially just for the first time. Whenever you save a file, first time or not, you can save it as anything, and there's no reason to have to save it as a .pdf. This eliminates answer choice D.
So the answer is C. it contains material you don't want changed.
Hope this helps!
B is your answer meteoroids are small space rocks they are usually pieces of asteroids or comets
I'm pretty sure it's C) or D) because it seems those make the most sense because providing excitement does not matter if that is not their point, repeating a previous point is practically useless because that point has already been said.
