What Is at the Focus of Earth's Orbit Around the Sun

What is at the focus of Earth's orbit around the Sun?

A) Nothing is at either focus
B) Nothing is at one focus, while the center of the Sun is at the other
C) The center of the Moon is at one focus, while the center of the Sun is at the other
D) Nothing is at one focus, while the center of mass of the Earth and Sun is at the other