Question

Cowbirds lay their eggs in the nests of smaller birds. The fast-developing cowbird chicks hatch first, then push the other nest as they hatch. The cowbird classified as a
(A) Pathogen
(B) Parasite
(C) Mutualist
(D) Commensal

Answer 1

Cowbirds rely on the other birds for their eggs to hatch properly. They can't provide sufficient heat and care required for hatching their eggs on their own, so they lay their eggs in another's bird's nest for their eggs to properly hatch. Once they are hatched, they move from that place.

Complete answer:
The method followed by cowbirds that is dependent on other organisms to fulfill our basic needs is known as Parasitism and the organism is known as a parasite.

Additional Information: This behavior of laying an egg on other’s nest is known as Brood parasitism and the organism is known as a brood parasite. Brood parasites are organisms that depend on others to take care of their young. The strategy appears among birds, insects, and fish. The brood parasite manipulates the host organism, either of identical or of another species, taking care of its young as if it were its own, using brood mimicry, as an example by having eggs that resemble the host's (egg mimicry).
Mutualism is the interaction between two or more organisms where both organisms can have the benefit of the interaction. An example is bees and flowers, Bees get nectar and flowers get pollinated in return.
Commensalism is when two species interact and one gets benefits, but another organism is neither harmed nor benefited. An example is remora fish and shark. Remora attaches itself to the shark at its belly for its transportation and food. This remora can travel to different areas without spending energy and the leftover food of the shark was eaten by this fish. Sharks are neither benefited or harmed.
The pathogen is the term used for disease-causing bacteria.
So, the correct answer is ‘Parasite '.

Note: The parental-care parasitism significantly increased the breeding number of the parasite, only about half the parasite eggs survived. The brood parasite also has significant drawbacks. For example, the parasitic offspring of the bearded tits, compared to the offspring in non-parasitic nests, tend to develop way more slowly and sometimes don't reach full maturity.