It is 4. because it says in the paragraph and I quote: "helium has a very low density. it is used in daily weather balloons to carry instruments that record, tempature, humidy, and pressure readings in the atmosphere.
One for an author to manipulate time in a passage is by Using Flashback to manipulate time.
With flashback, the author could manipulate thee flow of the story, revealing what happen in different timeline to create one connecting story line
hope this helps<span />
