Question

Which is a primary consumer?
A. scavenger
B. saprophyte
C. carnivore
D. herbivore

Answer 1

Hint: The primary producers which are eaten by the organisms are known as primary consumers. Generally, some plant-eaters, bacteria, and algae eaters are the primary consumers.
The primary consumers which are eaten by other organisms known as secondary consumers. Generally animals or meat-eaters, and carnivores are considered secondary consumers.

Complete answer:
Usually, this type of organisms (primary consumers) takes up the second trophic level and is fed upon or predated by secondary consumers, tertiary consumers, or apex predators.
The herbivores which feed on autotrophic plants are usually known as primary consumers. Autotrophic organisms are those living organisms (or plants) which produce their food through photosynthesis.
By using primary consumers, several other feeding strategies are also used. Photosynthetic algae are the food for carnivores.
 Several different feeding strategies are adopted by many primary consumers to adapt to maximize the effectiveness of foraging behavior.
Specific physiological adaptations are mainly for primary consumers that allow the primary consumers to process the carbohydrates produced through photosynthesis, which can be hard to break down and extract nutrition from. Many primary consumers also have symbiotic bacteria, which live within a special organ called the cecum. In all biomes and filling a wide variety of niches, the primary consumers exist.

Hence, the correct answer is option D. Herbivore is a primary consumer.

Note:
As we know that the herbivore is an animal that is a primary consumer and lives only by consuming plants.
A special digestive system is there for the herbivores animals where all kinds of plants digest including grasses. Mutualistic gut flora is present for a large percentage of herbivores animals which helps them digest the plant material in the stomach.