Select the correct answer.
Why are biologists still debating the classification of protozoans?

A.
Biologists never agree on anything.

B.
There are estimated to be over 50,000 different species.

C.
Protozoans can be heterotrophic or autotrophic.

D.
Protozoans can be unicellular or multicellular.

B

Explanation:

Answer B is correct:

Because the biologists are continuing to learn more and more about

such minute organisms, protozoan systematics – that is,  the taxonomy (classification) and the evolutionary interrelationships of major groups of protozoa – remains a  topic of debate and change, still today.

Some of the rather  LARGE and unwieldy taxonomic groupings of past years are  particularly subject to revision with expansion of and  refinement in the knowledge about the members of those –  and related – assemblages. Paradoxically, the protozoa  themselves are becoming more difficult to define with  precision as our information about them and other microbial assemblages increases. Thus, presenting a single  satisfactory circumscribed definition for them is not an  easy task.

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Answer A sounds so funny.

Answer C and D are false because Protozoans are usually single-celled and heterotrophic.

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Hope this answer can help you. Have a nice day!