Question

A scientist would build a model to observe what?

how cars are built
how the planets revolve around the sun
how high a dog can jump
how water boils and turns to steam

Answer 1

How the planets revolve around the sun. This is the most known observation scientist would want to discover with a model and also the only accurate choice to make a model for. So answer B

Hope my answer is correct. Also hope this helps :)

Answer 2

how the planets revolve around the earth.. since you can't approach some of them . which are far from the earth.. thus it is quite obvious that they should build a solar system and how planets integrate and move around the dynamic space time