"You are reading a book or a newspaper."
Translation:Vi legas libron aŭ ĵurnalon.
The other two options were so ridiculous that only a random selection could lead to a wrong answer. In multiple choice.
You add the accusative -n when the noun is the direct object of the sentance. A direct object is the thing that is receiving the action of a verb. For example:
La knabo manĝas la pomon.
Which means "The boy eats the apple." What is being eaten? The apple, because it ends in -n.
You have to add -n to some vowels because if that noun is being performed on it must have a suffix of -n. For example, La viro kisas virinon (the man kisses the woman). Since the man is kissed the woman she must have a -n at the end because she is the noun/object being performed on.
If you you mean "Ĉu" (with the hat), then you are correct. It turns a sentence into a yes/no (or multiple choice) question. Be careful when it comes to the hatted letters. If you can't type them on your keyboard, I use the Google keyboard, which has esperanto language support. Or you could, as a last resort, use the x-system.