Final answer:
Option B, which suggests adding more details about factors affecting intelligence tests, will most help Donovan improve his essay's clarity and cohesiveness, while option D is the least helpful as it offers no actionable advice.
Step-by-step explanation:
The piece of feedback that will most help Donovan improve the clarity and cohesiveness of his writing is B. I think that you could go into a bit more detail about factors that affect the results of intelligence tests. This suggestion prompts Donovan to elaborate on specific factors, providing a clearer and more coherent understanding of the intelligence tests within his essay. Conversely, the least helpful feedback for improving clarity and cohesiveness is D, I really like your organization in this paragraph, because it offers praise without any direction for improvement or development.