Which of the following are also called producers?
Green plants
The explanation for the incorrect option(s):
A: Cows
A cow is a consumer because it is unable to produce its own food. Cows must consume plants (which are producers) in order to survive.
B: Rabbits
Rabbits are consumers. They eat producers, such as grasses.
C: Humans
Humans are an example of a tertiary consumer. Both secondary and tertiary consumers must hunt for their food, so they are referred to as predators.
The explanation for the correct option:
D: Green plants
Hence, option D is correct.