A) Seeds are eaten by a sparrow, the sparrow is eaten by a hawk, and the hawk's eggs are eaten by a snake.
B) Seeds and grasses are eaten by various insects and small herbivores, the insects are eaten by a meadowlark, the small herbivores are eaten by a hawk, the meadowlark and hawk eggs are eaten by snakes, and the snakes are eaten by owls.
C) Goats eat grass; the goats are milked and eaten by humans.
D) Seeds are eaten by a tufted titmouse, the titmouse is eaten by a hawk, the hawk eggs are eaten by snakes, and the snakes are eaten by owls.

A) have clearly fixed boundaries and are always defined on the same scale.
B) can be nested within larger ecological communities.
C) are defined as groups of four or more species within a given area.
D) are groups of species that do not fluctuate over time.

A) producer and primary consumer
B) primary and secondary consumer
C) secondary and tertiary consumer
D) producer and primary consumer.