Answer:
The correct option is b. new species make the environment less suitable for previous ones.
Step-by-step explanation:
In ecology, succession can be described as the changes in a species structure over a period of time. In a community, newer species tend to have better characteristics and adaptations to survive in a community as compared to the older ones. As a result, the new species begin to take over the land and the older ones gets removed. It is due to ecological succession that climax communities are formed from pioneer species.