The three correct answers that describe the differences between solar wind and geomagnetic storms are:
a. solar wind sometimes results in geomagnetic storms; geomagnetic storms do not cause solar wind
b. geomagnetic storms are associated with CMEs; solar wind is associated with the constant activity in the sun
c. geomagnetic storms occur only occasionally; solar wind is constant
These answers differentiate the nature and characteristics of solar wind and geomagnetic storms effectively.