This is a test of commonsense with single/multi-choices. Complete the next sentence:

How to cover a book
Choose paper to cover your book with.
For books without covers or to protect your textbooks, make a paper cover for your book. You can cover your books with foreign or old newspapers, old or new maps, sheet music, old wall paper, a brown paper bag, etc.. unless you are covering a smaller book, you will need a large piece of paper to make your cover.

Options are:
[a]. It will need to be at least double the length of your book and three inches taller than the height of your book. Cut the paper to size using the measurements for your book.;
[b]. Choose a paper that is a similar color to the book. Measure your book so that you have a rough line of " 50 " where the spine meets the book margin.;
[c]. An idea of what color paper to use is to use colored cardstock that is of a color. This is much easier for covering books with than paper with a color.;
[d]. If you're covering an anthology, pre-printed or notebooks will work. Certain sizes of paper may be too large.;
The answer is:
[a].