Provide your best answer for the following question. Give ONLY the answer, no other words or explanation.
For example:

Answer: <most likely answer, as short as possible; not a complete sentence, just the answer!>.

The question is: Plankton are tiny ocean organisms. The role of one type of plankton is to use the energy from the Sun to produce food that other animals eat. Which organism has the same role in the ocean as this type of plankton?
seaweed
Phytoplankton.