Answer the following question given this paragraph: 

Einstein’s equation is part of a larger theory called the theory of relativity. It is concerned with concepts such as motion and forces as well as mass and energy. Motion and forces are the focus of succeeding chapters.


Q: What larger theory is einstein's equation part of?

 Choices:

- excess of relativity

- cycle of relativity

- law of relativity

- theory of relativity

A:
theory of relativity
