Shorter/longer food chains provide more energy.

Explanation

**Step-by-Step Solution:**

1. **Understanding Energy Transfer in Food Chains:**
- In any food chain, energy is transferred from one trophic level to the next. However, not all the energy is passed on; a significant portion is lost at each level.

2. **The 10% Law:**
- According to the 10% law of energy transfer, only about 10% of the energy from one trophic level is passed on to the next level. This means that if a producer (like a plant) has 100 joules of energy, the primary consumer (herbivore) will only receive about 10 joules.

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