Answer the following question given this paragraph: 

The smallest particle of an element that still has the properties of that element is an atom. Atoms are extremely tiny. They can be observed only with an electron microscope. They are commonly represented by models, like the one Figure below . An atom has a central nucleus that is positive in charge. The nucleus is surrounded by negatively charged particles called electrons.


Q: What is the smallest particle of an element that still has the properties of that element is called?

 Choices:

- nucleus

- neutron

- proton

- atom

A:
atom
