In a grassland, two primary consumers feed on the same grass. Consumer X has lower biomass than Consumer Y, yet X receives more energy from producers per unit time.  Which explanation BEST resolves this paradox?
1. X feeds more frequently or rapidly than Y 
2. X occupies a higher tropic level 
3. Y has higher assimilation efficiency 
4. Energy pyramids can be inverted in grasslands 
Subtopic:  Energy Flow |
Level 3: 35%-60%
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