A physician who specializes in treatment of the gums is called a periodontist.
Food webs normally start at the bottom and work their way up. Like the plants will be at the bottom, and then each level shows the animals getting bigger while losing energy. You continually lose energy as you work your way up an ecosystem, so normally there are only three or four levels. I hope this helps!
Not sure but my best guess is to go with B. It just makes the most sense.
