In an ecosystem, primary consumers are herbivores that feed directly on producers (plants).
- The grasshopper is an herbivore and feeds on plants, making it a primary consumer.
- A snake (Option 2) is a secondary or tertiary consumer since it eats other animals.
- A fox (Option 3) is a tertiary consumer and also eats animals, not plants.
- A deer (Option 4) is also a primary consumer, but the best option for this question, given that grasshopper is a clear example of a herbivore, is grasshopper.
Thus, the correct answer is the grasshopper.