When the structure and function of an organism adjusts to its environment it is adapting.
The answer is the last one. Countercurrent multiplication in the kidneys is the way toward utilizing vitality to create an osmotic slope that empowers you to reabsorb water from the tubular liquid and deliver concentrated pee. It is discovered broadly in nature and particularly in mammalian organs.
Countercurrent multiplication was initially considered as a system whereby pee is gathered in the nephron. At first, concentrated in the 1950s by Gottschalk and Mylle following Werner Kuhn's hypotheses, this instrument picked up notoriety simply after a progression of confounded micropuncture tests.
If the producer were to disappear then all the other organisms will either go extinct, survival of the fittest, or have to adapt to the change.
The answer is D, algae.
—Evidence—
•] Protozoan definition: a single-celled microscopic animal of a group of phyla of the kingdom Protista, such as an amoeba, flagellate, ciliate, or sporozoan.
•] it does not feature algae, therefore it’s D.