1.
C. Later
When something is arranged in chronological order, it means events are listed by time. The story is shown as a sequence of events, the best way to illustrate it is with a timeline. The word later is the only one that specifically refer to time, it refers to a situation that is after the present one or the one you have been refering to.
2.
C. Don’t believe every last word you hear about computer viruses. The experts get it wrong.
Remember that informal writing is the one used on a regular conversation. It allows contractions and abbreviations, adressing the audience using second person, the first or third point of view and the use of slang. Options B., C., and D. use this kind of writing. The key is to keep in mind that this is a school project or homework so we need to watch our language. I think that options B. and D. are too informal for using them in school so option C. is the one in which a contraction is used and the reader is directly adressed by using second person.
