The correct answer is D. Ecosystems are always smaller than a biome.
Step-by-step explanation
A biome is a set of abiotic factors that form a territory in which different organisms inhabit. In addition, biomes encompass a set of ecosystems such as tundra, rainforest, savannas, wetlands, among others. On the other hand, an ecosystem is a community of organisms that interact with other organisms and abiotic factors. According to the above, the correct answer is D. Ecosystems are always smaller than a biome becaause biomes includes ecosystems with similar features.