Answer:
Family secrets shouldn't be told outside of the family because whoever told ypu that secret trusted you alot to keep the secret and just as you gained there trust you can lose it.
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.
End, to summarize what you are talking about.
I believe 4 would be incorrect.