If a mouse eats grass, a snake eats the mouse, and an eagle eats the snake, what is the eagle ?
a. producer.
b. secondary consumer.
c. primary consumer.
d. tertiary consumer.

Tertiary :)
grass = producer
mouse = primary
snake = secondary

The eagle would not be a producer or a primary consumer. The snake is the secondary consumer and the grass is the producer and the mouse is the primary consumer. So the eagle is the tertiary consumer. D

Because the carnivores keep the herbivore population in check