Gizmo student cell division answer key?

i think that d. wind is the answer.   i missed the question when i answered a. currents.

because of

primary succession occurs in essentially lifeless areas regions in which the soil is incapable of sustaining life as a result of such factors as lava flows, newly formed sand dunes, or rocks left from a retreating glacier. secondary succession occurs

the question isn't complete here so i can't right an answer '_'