To What Does the Term 'Milankovitch Cycles' Refer

To what does the term 'Milankovitch cycles' refer?

A) Changes in Earth-Sun relationships,namely Earth's orbit around the sun,Earth's axial rotation,and Earth's axial tilt.
B) Cyclical changes in solar irradiance caused by increases and decreases in sunspot activity.
C) Increases and decreases in atmospheric gases and aerosols,primarily caused by natural activity such as volcanic activity and changes in net primary productivity.
D) Tectonic changes in continental position and topographic changes from orogeny,erosion,and mass wasting.