Answer:
a
. ecological succession, because each community promotes the growth of the succeeding community
Step-by-step explanation:
Ecological succession is the process in which species structure of an ecological community changes over time.
The given example shows ecological succession (secondary succession) as in the image series of community changes over hundred of years including growth of community from bare rocks to trees as each community is promoting growth of succeeding community. But the colonized community of trees after series of changes is disturbed by human activities or natural calamity (as shown in image) reduces an already established ecosystem is called secondary succession (Type of ecological succession).
Hence, the correct option is a. ecological succession, because each community promotes the growth of the succeeding community