Explanation
Correct answer: D.
Choice D is the best answer. The sentence explains what harvestmen are, noting that they are also known as daddy longlegs and that they are arachnids but not spiders.
Why the other choices are wrong
Choice A
Choice A is incorrect. While the sentence does mention harvestmen, its main focus is on spiders. Moreover, it misrepresents information from the notes: harvestmen are not spiders.
Choice B
Choice B is incorrect. The sentence focuses on the broader point that arachnids include more than just spiders; it doesn’t mention harvestmen directly or explain what they are.
Choice C
Choice C is incorrect. The sentence focuses on how daddy longlegs are classified; it doesn’t explain what harvestmen are. Moreover, it misrepresents information from the notes. The notes indicate that harvestmen are not spiders, and “harvestmen” is presented in the notes as an alternate name for “daddy longlegs,” not a category in which daddy longlegs belong.