I believe the pronoun in this sentence is <u>your key</u>.
Knows little. 2 and 3 are both presuming too much, as it's the writer's duty to get them interested and informed. 4 basically doesn't matter, and furthermore may not even apply in many forms of writing. 1 is the best answer, as writing for general audiences is intended to inform and expand the horizons of the reader.
Five paragraphs including an intro, outright, and 3 body paragraphs with whatever subject.
