Primary succession can occur after a

Devastating event

Primary succession usually takes place when after a devastating event , the entire life forms on a particular land gets wiped out and a new land is formed. For example – Eruption of a volcano causes the flowing of lava, which being extremely hot destroys every thing in its path. When the lava coold down a new land would have been formed as it consists of nothing living in that area.  

it's     c       this is a cell (b) with a nucleus (c) containing dna (a). the dna is organized into chromosomes (d). a section of the chromosome that codes for a trait is called a gene (e).

is this a psat question, if so do not cheat try your best.