1. The problem asks: Which structure of a leaf prevents excessive loss of water from the leaf surfaces? 2. The formula or concept here is related to plant anatomy and physiology. The leaf has several layers and structures, each with specific functions. The cuticle is a waxy layer that covers the leaf surface and prevents water loss. 3. Important rule: The cuticle is the primary barrier to water loss in leaves, while other layers like the spongy layer and palisade layer are involved in photosynthesis and gas exchange. 4. Intermediate work: - Spongy layer: involved in gas exchange, not water loss prevention. - Palisade layer: contains chloroplasts for photosynthesis. - Cuticle: waxy, waterproof layer that reduces water loss. - Air spaces: facilitate gas exchange. 5. Therefore, the correct answer is C. Cuticle. Final answer: **C. Cuticle**