As @Naz pointed out in the other thread here, the argument in the passage is describing a part to whole flaw.
It explains that since it is wrong for an individual to have the power to choose the course of action for a government, then it to wrong for society to have this power since society is made up of many individuals. Therefore, the ancient Greeks failed to realize that democracy is no improvement over monarchy.
Our correct answer choice will have another part to whole flaw.
Answer choice (D) has exactly this.
We are told that since no one member of the club can afford one of those tents, the club is also unable to afford one of those tents, so there is no point in asking the club, which is made up of members, to purchase tents and make them available for use by club members.
Now let's take a look at (A):
"There is no point in trying to find someone else to solve that problem. If Robin cannot solve it, then none of Robin's friends would be able to solve it."
This argument is definitely flawed but this is not the same part to whole flaw that we saw in the stimulus.
The flaw in (A) has to do with a general principle, which deals with Robin and Robin's friends, that is not invoked but yet somehow supports a conclusion related to finding anyone else at all (notice the conclusion here is not limited to Robin and his friends). For this reason, (A) would be incorrect.
Hope that helps! Please let us know if you have any other questions.
