Answer: 
The correct answer is option B. 
Explanation: 
Protists are not monophyletic, meaning that they did not represent a single, whole branch of the common life form. 
A paraphyletic group is the group of some descendants of a common ancestor. Protists are considered a paraphyletic group. 
Example of the monophyletic group is mammals as each and every mammal share a common single ancestor that is not shared by another group of organism.
Thus, the correct answer is option B.