Most likely B. Information is organized with text features, such as headings.
Functional texts are designed to be used for the purpose of fulfilling a particular need or to solve a problem. They usually come in the form of a manual or guide book, something you can skim through to find the particular thing you need to know.
A- They do not normally have opinions, only facts and guide lines.
C- The level of importance depends on the job you are doing, not all information will be useful, which may change when you look at it again for a different job/project/problem.
D- They do not normally have a "central narrative", because that would mean it had a point of view, which manuals do not have.
I hope this helps and I answered the right question for future reference.