can someone answer this? id appreciate it !!

What is the main difference between primary succession and secondary succession?

a.) In primary succession, there are only a few organisms present; in secondary succession there are many organisms in place.

b.) In secondary succession, the soil needs to be made; in primary succession it is already present.

c.) In primary succession, a weather disaster will affect the land; in secondary succession it is a geological disaster.

d.) In primary succession, the soil needs to be made; in secondary succession it is already present.