Final answer:
The upper limit of rocky intertidal communities is typically determined by wave action, which creates a harsh environment that only specially adapted organisms can survive.
Step-by-step explanation:
The upper limit of rocky intertidal communities is typically determined by a variety of environmental factors. However, among the options provided, the key factor that determines the upper limit is wave action. The intertidal zone experiences constant ebb and flow of tides, leading to periods of submersion and exposure. Organisms in this zone, like barnacles and shore crabs, have adapted to these conditions with tough exoskeletons to protect against desiccation and wave damage. The pounding waves make it difficult for algae and plants to establish themselves, thus affecting the upper limit of this ecosystem.
While sunlight, temperature, and oxygen levels are important for life in marine biomes, they are not the primary factors determining the upper limit of rocky intertidal zones. Wave action's physical impact creates a boundary only the most adapted organisms can tolerate, resulting in a distinct upper limit of this ecological community.