Please help will give a a lot of points

Which of these sentences is the correct one?

When should you use encyclopedias such as wikipedia? a. never, it is not appropriate to use this source in college b. it can you get an overall understanding of the subject matter but is not considered a college-level source c. as long as wikipedia isn't the only source, it is always appropriate to use this source

Which organizational method does your reading material suggest is particularlyuseful when writing about a place? of importancecause → effect