The modern atomic model is also sometimes called the model.
a. quark
b. einstein
c. final frontier
d. quantum mechanics

A) Quark is incorrect, because it is a particle (very small).

b) Einstein was a man, not a model. -_-

c) Final frontier was not a model also.

d) We are left with our best answer, quantum mechanics. It is the correct answer! It is used by modern physicists. 

Final - d) quantum mechanics