Answer :
Final answer:
A keystone species is (a) one that serves as a cornerstone of an ecosystem, exerting a disproportionate influence on its environment, and restoring it can help stabilize the ecosystem
Explanation:
A keystone species is a species whose presence and activities have a significant impact on the structure and functioning of an ecosystem.
While keystone species may not necessarily be the most abundant species in an ecosystem, they play critical roles in maintaining biodiversity and ecosystem stability.
Keystone species can have far-reaching effects on community structure and function, often influencing the abundance and distribution of other species.
Restoring a keystone species can be essential for ecosystem restoration efforts because it can help stabilize and restore the ecological balance within the ecosystem, hence the correct answer is A) A keystone species is one that serves as a cornerstone of an ecosystem, exerting a disproportionate influence on its environment, and restoring it can help stabilize the ecosystem