What percentage of energy from producers is stored in the trophic level of the island fox?

• Producers (like the Manzanita tree or Cactus) are at the first trophic level.
• Primary consumers (like the Grasshopper or Mouse) eat producers, forming the second trophic level.
• The Island fox, when it eats primary consumers (like a Grasshopper or Mouse), acts as a secondary consumer, placing it at the third trophic level.

The 10% rule states that only about 10% of the energy from one trophic level is transferred to the next trophic level. The remaining 90% is lost, primarily as heat during metabolic processes.

• If producers have 100% of the initial energy.
• Primary consumers (e.g., Grasshopper, Mouse) receive 10% of the producers' energy: $$100\% \times 0.10 = 10\%$$
• Secondary consumers (Island fox, eating primary consumers) receive 10% of the primary consumers' energy: $$10\% \times 0.10 = 1\%$$

The island fox, as a secondary consumer in this food chain, stores approximately 1% of the energy originally present in the producers.

The final answer is $\text{C}$