A student wants to make a simple model of the solar system to help him compare how long it would take for a spaceship to travel between different planets. Which of the following things is essential for him to do in order to think about how long it would take?

He must make sure that the model of each planet looks like the planet it represents, but he does not need to accurately represent the relative distances between the planets because the most important thing is that models look like the thing they are modeling.

He must accurately represent the relative distances between the planets, but he does not need to make sure that the model of each planet looks like the planet it represents because only the relevant aspects of the thing being modeled need to be modeled accurately.

He must accurately represent the relative distances between the planets and also make sure that the model of each planet looks like the planet it represents, because a model should be as much like the thing being modeled as possible.

He does not need to accurately represent the relative distances between the planets, and he does not need to make sure that the model of each planet looks like the planet it represents, because there are always some differences between a model and the thing being modeled.