With regard to the assertion and reason, choose the correct option.
Assertion [A]: Extinctions have a domino effect.
Reason [R]: The extinction of one species affects the survival of other species that are in obligate relationship with the extinct one.
Most species co-evolve in their natural habitat; therefore most organisms have deep-rooted and sometimes obligate relationships with other species in their habitat. For e.g., an obligate predator, parasite or a pollinator. When one such organism is lost, their relationships are also lost, thereby threatening the survival of other species that are associated with it, either through mutualistic, predatory or parasitic relationships.