Answer:
Increased keystone species
Step-by-step explanation:
An organism is a keystone species when it contributes to the definition of a given ecosystem such that the absence of the keystone species in an ecosystem, the ecosystem will change dramatically or be gradually wiped out
The effect of the keystone on its environment is unevenly large when compared to its abundance relative among other organisms within the ecosystem
The keystone is therefore, a prime source of balance of nature, diversity and well-being of the ecosystem
Therefore, the option that contributes to the diversity of the ecosystem is;
Increased keystone species.