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.
The Big Dipper is an asterism in the constellation Ursa Major (the Great Bear). One of the most familiar star shapes in the northern sky, it is a useful navigation tool. Asterisms are prominent groups of stars that form patterns but are smaller than, or even part of, a constellation.
If I was trying to reduce my debt I would first cut unnecessary food expenses.
