No , most of Protozoa are not photosynthetic hence can't produce O2 .
wheat
Most of the worlds oxygen is produced by Trees.
To me the answer to this question is starch
The Honda 50cc single cylinder OHC engine (Supercub) is the world's most produced engine (over 80 million units)
Only some protozoa are decomposers as giant Amoeba . Most protozoa are saprotrophic , some parasitic and some photosynthetic .
the worlds most sold car was the German 1938 vw beetle selling way over 21,000,000 of them, it was produced up to 2003 in the factory in Brazil.
They are Unicellular.
The protozoa are one-celled animals and the smallest of all animals. Most of them can only be seen under a microscope.
Well energy is a broad topic, in-terms of oil the US uses the most, roughly 25% of the worlds oil that is produced.
The most produced engine is the original Chevy/GM V-8 small block, produced from 1955-2003 for production vehicles, still produced as a replacement engine, and still widely used both in existing vehicles and as a performance/race engine. Approximately 90 million have been made.
The protozoa are larger and easier to see. There are a lot more bacteria because after all they are what the protozoa are feeding on but they at the very limit of resolution for most light microscopes. They are also less obvious because most don't move.
Most of the world's oxygen is produced by phytoplankton in the ocean. These microscopic marine plants carry out photosynthesis, using sunlight to convert carbon dioxide into oxygen. Phytoplankton play a vital role in producing oxygen and supporting marine ecosystems.