Based on the lessons regarding the Principle of Fossil Correlation, it asserts that rock layers containing identical fossil groupings are reflective of the same geological age.
The right answer is option d as its absence would impact many organisms in the ecosystem.
Keystone species are crucial for the ecosystem's health. If such a species were to disappear from an ecosystem, it would disrupt the ecosystem's functioning, leading to significant consequences. Therefore, keystone species are vital for the ecosystem's survival.
