Energy in an ecosystem flows directly from a. producers to tertiary consumers
b. producers to secondary consumers
C. tertiary consumers to secondary consumers
d. secondary consumers to tertiary consumers

energy enters an ecosystem through photosynthesis. By feeding on plants and on one another, animals play an important role in the movement of the matter/energy though. they also influence the quantity of plant and biomass present. so the anwser is D, secondary consumers to tertiary consumers

''d' is correct.

Explanation:

Producers-->Primary Consumers-->Secondary Consumers-->Tertiary Consumers

the answer will be a) proteins i believe

"a.) well–developed vascular system."