The correct answer is phytoplankton production is necessary to begin a food web in an ocean ecosystem.
A food chain is a single pathway which connects a producer to several levels of consumers whereas in a food web there are several connected pathways or food chains from producers to consumers in a particular habitat. a food chain can be considered a part of the food web.
The basic foundation of the food chain or a food web of the ocean are the single celled organisms called phytoplanktons which are saturated in the sunlit upper layer of the ocean water. The phytoplanktons consist of small plants and bacteria which capture the energy from sunlight and convert them to nutrients and organic compounds by the process of photosynthesis. The phytoplanktons are the primary producers of ocean ecosystem followed by herbivores or zooplanktons such as jellyfish and mollusks and then followed by carnivores such as octopus and sardines and the top predators like sharks, tuna and dolphins are top predators of several food chains or part of the ocean food web.
