What is the main purpose of scientific models?
a. the main purpose of models is to have a physical object to which to refer.
b. the main purpose of models is to represent observations.
c. the main purpose of models is to study systems that no longer exist.
d. the main purpose of models is to gain a better understanding of the world.

b. The main purpose of models is to represent observations.

Explanation:

Since we are talking about scientific models, we are talking as well about implementing the scientific method, which is based on observations. Scientists record their observations, plan and conduct experiments based on that and then collect data. It is once they have acquired the data that scientists may recurr to the usage of models in order to constitute ideas, processes or systems to describe and explain phenomena, using scientific models to represent observations.

the correct option is option d