Answer: The correct answer is geographical map.
Step-by-step explanation:
Model is defined as the three dimensional representation of a proposed structure in a smaller scale.
For the given options:
Option 1: PV = nRT
This is a proposed law. This law is known as ideal gas law. A law is defined as the rule which defined a correct procedure. For any gas behaving ideally, this law is used.
Option 2: Geographical map
Map is defined as the diagrammatic representation of an area of land or sea which also shows physical features, roads, cities etc..
A 3-D model can be prepared for geographical map.
Option 3: I believe that aliens exist
This is a hypothetical statement. It is a smart guess by the means of set of assumptions and observations. For its validation, we need to conduct some experiments.
Hence, the correct answer is geographical map.